UC-NRLF 


1 

THE   GASOLINE 
MOTOR 

BY  HAROLD  WHITING  SLAUSON,  M.  E. 


THE  GASOLINE  MOTOR 


THE  GASOLINE 
MOTOR 


BY 


HAROLD  WHITING  SLAUSON,  M.  E. 

AUTHOR  OF  "THE  MOTOR  BOAT*' 


QUT-ING 


HANDBOOKS 


NEW  YORK 

OUTING   PUBLISHING   COMPANY 
MCMXIII 


X 


COPYRIGHT,  1913,  BY 
OUTING  PUBLISHING  COMPANY 

All  rights  reserved 


CONTENTS 


I.  TYPES  OF  MOTORS       .     .     .     ,..      9 
II.  VALVES 24 

III.  BEARINGS 43 

IV.  THE  IGNITION  SYSTEM      ...     62 
V.  MAGNETOS 83 

VI.  CARBURETORS  AND  THEIR  FUEL  .     90 

VII.  LUBRICATION 112 

VIII.  COOLING 130 

IX.  Two  CYCLE  MOTORS     .      .      .     148 


263630 


THE  GASOLINE  MOTOR 


THE  GASOLINE 
MOTOR 

CHAPTER  I 
TYPES  OF  MOTORS 


THERE  are  certain  events  that  must  hap- 
pen in  a  gasoline  motor  before  the  en- 
gine will  run  of  its  own  accord.  For  in- 
stance, to  obtain  successive  power  impulses,  the 
charge  must  first  be  admitted  to  the  cylinder 
and  compressed;  it  must  then  be  ignited  to 
form  the  explosion  that  creates  the  force  at  the 
flywheel;  and  the  burned  gases  resulting  from 
this  explosion  must  be  ejected  in  order  to  clear 
the  cylinder  for  the  new  charge.  To  ac- 
complish this  series  of  events,  some  motors  re- 
quire four  strokes,  while  others  do  the 
business  in  two.'  These  are  popularly  called 
four-cycle  and  two-cycle  motors,  respectively. 
A  cycle,  of  course,  can  be  any  round  of 
events,  such  as  a  cycle  of  years — at  the  end  of 
which  time  the  previous  happenings  are 
scheduled  to  repeat  themselves.  But  in  gas  en- 
gine parlance  a  cycle  is  taken  to  mean  the 
round  of  events  from,  say,  the  explosion  of  one 
charge  to  the  ignition  of  the  next.  Thus,  it 

9 


10      THE  GASOLINE  MOTOR 

will  be  seen  that  the  four-cycle  motor  requires 
four  strokes  of  the  piston  to  accomplish  its 
round  of  events,  and  is,  properly,  a  four-stroke 
cycle  motor.  Likewise,  the  so-called  two-cycle 
motor  requires  two  strokes  to  complete  its  cycle 
and  should  therefore  be  termed  a  two-stroke 
cycle  motor. 

If  this  longer  terminology  could  be  adhered 
to,  there  would  be  less  misunderstanding  of  the 
meanings  of  two-  and  four-cycle,  for  when 
taken  literally,  these  abbreviated  forms  signify 
absolutely  nothing.  Usage  seems  to  have 
made  them  acceptable,  however,  and  if  the 
reader  will  but  remember  that  four-cycle,  for 
instance,  means  four  strokes  per  cycle,  the  term 
becomes  almost  as  simple  as  does  "  four- 
cylinder." 

It  is  evident  that  there  are  two  strokes  for 
.each  revolution  of  the  flywheel — one  when  the 
crank  is  forced  down  and  the  other  when  the 
crank  moves  up.  As  the  piston  is  attached  to 
the  crank  through  the  medium  of  the  connect- 
ing rod,  the  strokes  are  measured  by  the 
motion  of  the  piston.  Thus,  since  it  requires 
four  strokes  of  the  piston  to  complete  the 
round  of  events  in  the  four-cycle  motor,  the  ex- 
plosions occur  only  at  every  second  revolution 
of  the  flywheel.  In  this  connection  it  must  be 


TYPES  OF  MOTOR  11 

remembered  that  we  are  dealing  with  but  one 
cylinder  at  a  time,  for  a  four-cycle  engine  is 
practically  a  collection  of  four  single-cylinder 
units. 

But  even  though  the  explosion  in  a  four-cycle 
motor  occurs  only  every  other  revolution,  the 
engine  is  by  no  means  idle  during  the  interval 
between  these  power  impulses,  for  each  stroke 
has  its  own  work  to  do.  The  explosion  exerts 
a  force  similar  to  a  "  hammer  blow  "  of  sev- 
eral tons  on  the  piston,  and  the  latter  is  pushed 
down,  thus  forming  the  first  stroke  of  the  cycle. 
The  momentum  of  the  flywheel  carries  the  pis- 
ton back  again  to  the  top  of  its  travel,  and 
during  this  second  stroke  all  of  the  burned,  or 
exhaust,  gases  are  forced  out  and  the  cylinder 
is  cleaned,  or  "  scavenged."  The  piston  is 
then  carried  down  on  its  third  stroke,  which 
tends  to  create  a  partial  vacuum  and  sucks  in 
the  charge  for  'the  next  explosion. 

On  the  fourth,  and  final,  stroke  of  the  cycle 
the  piston,  still  actuated  by  the  momentum  of 
the  flywheel,  is  pushed  up  against  the  recently- 
admitted  charge  and  compresses  this  to  a  point 
five  or  six  times  greater  than  that  of  the  atmos- 
phere. At  the  extreme  top  of  this  last  stroke, 
the  spark  is  formed,  causing  the  next  explosion, 
and  the  events  of  this  cycle  are  repeated. 


12      THE  GASOLINE  MOTOR 

Now,  inasmuch  as  on  one  up-stroke  of  the 
piston  the  charge  must  be  held  tightly  in  place 
in  order  that  it  may  be  compressed,  and  on  the 
next  up-stroke  a  free  passage  must  be  offered 
so  that  the  exhaust  gases  may  be  forced  out,  it 
is  evident  that  a  valve  must  be  used  as  a  sentry 
placed  at  the  openings  to  restrain  the  desirable 
gas  from  escaping  and  also  to  facilitate  the  re- 
treat of  the  objectionable  exhaust.  Likewise, 
the  force  of  the  explosion  must  be  confined  to 
the  piston  on  one  down-stroke  in  order  that  all 
of  the  energy  may  be  concentrated  at  the  crank, 
while  on  the  succeeding  down-stroke  a  free  pas- 
sage must  be  afforded  to  the  charge  so  that  it 
may  be  sucked  in  through  the  carburetor.  Con- 
sequently a  second  valve  must  be  used  to  con- 
trol the  inlet  passage  on  the  down-strokes  and 
prevent  the  escape  of  the  force  of  the  explosion 
through  an  opening  that  was  intended  as  an  en- 
trance for  the  fresh  charge.  Thus  valves  are 
a  necessity  on  all  motors  in  which  successive 
similar  strokes  of  the  piston  do  not  perform 
the  same  operations. 

As  quadrupeds  and  bipeds  form  the  two 
great  divisions  of  the  animal  kingdom,  so  is 
the  motor  separated  into  the  two  main  classes 
of  four-cycle  and  two-cycle  engines.  Even 
though  to  all  exterior  appearances,  the  two 


TYPES  OF  MOTOR  13 

types  of  motors  may  be  identical,  the  distinc- 
tion, to  the  engineer,  at  least,  is  as  marked  as  is 
the  difference  between  a  stork  and  an  elephant. 
The  difference  is  somewhat  reversed,  however, 
in  that,  while  the  elephant  has  double  the  num- 
ber of  legs  of  the  stork,  the  four-cycle  motor 
has  but  one-half  the  number  of  power  impulses 
of  its  two-cycle  cousin  at  the  same  speed. 

In  other  words,  there  is  an  explosion  in  each 
cylinder  of  the  two-cycle  motor  with  every 
revolution  of  the  flywheel, — instead  of  with 
alternate  revolutions,  as  is  the  case  with  the 
four-cycle  type.  But  the  number  of  events 
necessary  to  produce  each  explosion  must  be 
the  same  in  both  types  of  motors,  and  con- 
sequently it  is  only  by  "  doubling  up  "  and  per- 
forming several  operations  with  each  stroke 
that  the  two-cycle  motor  can  obtain  a  power 
impulse  with  each  revolution  of  the  flywheel. 

Starting  with  the  ignition  of  the  charge,  as 
in  the  four-cycle  motor,  let  us  see  how  the 
events  are  combined  in  the  two-cycle  type  so 
that  all  will  occur  within  the  allotted  two 
strokes.  Directly  after  the  explosion  there  is 
but  one  event  that  can  happen  if  this  force  has 
been  properly  harnessed,  and  that  is  the  vio- 
lent downward  travel  of  the  piston.  Just  be- 
fore the  bottom  of  this  downward  stroke  is 


14      THE  GASOLINE  MOTOR 

reached,  however,  an  opening  is  uncovered 
through  which  the  exhaust  gases  can  expend 
the  remainder  of  their  energy — which  by  this 
time  has  become  greatly  reduced.  Immediately 
after  this  another  passage  is  uncovered  and  the 
charge  is  forced  into  the  cylinder  under  pres- 
sure, thus  helping  to  clear  the  cylinder  of  the 
remainder  of  the  exhaust  gases. 

All  of  this  takes  place  near  the  end  of  the 
down-stroke;  and  at  the  beginning  of  its  return, 
the  piston  closes  the  openings  previously  un- 
covered for  the  passage  of  the  exhaust  gases 
and  incoming  charge,  and  then  compresses  the 
mixture  during  the  remainder  of  its  up-stroke. 
Thus  the  suction  stroke  and  the  "  scavenging  " 
stroke  of  the  four-cycle  motor  are  dispensed 
with  in  the  two-cycle  type  and  every  downward 
thrust  of  the  piston  is  a  power  stroke. 

The  two-cycle  motor  has  been  used  in  sev- 
eral notable  instances  with  great  success  on 
motor  cars,  but  by  far  the  larger  majority  of 
automobile  power  plants  are  of  the  four-cycle 
type.  In  view  of  the  wonderful  simplicity  of 
the  two-cycle  motor,  its  small  number  of  mov- 
ing parts,  and  its  more  frequent  power  im- 
pulses, it  may  well  be  asked:  "  Why  is  this  not 
in  more  popular  use  on  the  motor  car?  "  The 
four-cycle  motor  has  but  one  power  stroke  out 


TYPES  OF  MOTOR  15 

of  every  four,  while  only  alternate  strokes  of 
the  two-cycle  motor  consume  power  without 
producing  any. 

This  would  seem  to  indicate  that,  for  equal 
sizes  and  weights,  the  two-cycle  motor  would 
produce  twice  as  much  power  as  the  four-cycle 
type — and  this  is  true  theoretically.  But  the 
four-cycle  motor  devotes  an  entire  stroke  to 
forcing  out  the  exhaust  gases,  or  scavenging, 
and  another  entire  stroke  to  drawing  in  a  fresh 
charge,  and  it  is  evident  that  these  operations 
can  be  done  much  more  effectively  in  this  man- 
ner than  when  combined  with  several  other 
events  following  each  other  in  such  rapid  suc- 
cession as  is  the  case  with  the  two-cycle  motor. 
In  the  two-cycle  motor  the  incoming  charge 
must  be  diluted  to  a  certain  extent  with  the  ex- 
haust gases  which  have  not  been  entirely  ex- 
pelled, and  the  intake  valve  port  is  uncovered 
for  so  short  a  time  that  unless  there  has  been 
very  high  compression  in  the  base,  the  cylinder 
cannot  be  entirely  filled  with  the  explosive  mix- 
ture at  high  speeds.  This  is  described  in 
greater  detail  in  the  last  chapter  of  this  volume. 
Thus,  while  admittedly  simpler  in  construction 
and  operation  than  the  four-cycle,  the  two- 
cycle  motor  in  its  ordinary  forms  does  not  ob- 
tain quite  as  high  an  efficiency  from  the  fuel  as 


16      THE  GASOLINE  MOTOR 

does  its  more  complicated  cousin.  Each  type 
has  its  distinct  use,  however,  and  in  many  in- 
stances in  which  low  initial  cost  and  simplicity 
of  design  are  more  desirable  than  are  econ- 
omy of  fuel  and  high  efficiency  of  operation, 
the  two-cycle  motor  stands  supreme. 

The  sentries  that  stand  guard  over  the  pas- 
sages through  which  the  gases  make  their  en- 
trance and  exit  may  appear  in  a  variety  of 
guises,  but  they  determine  the  shape  of  the 
cylinders  of  a  motor  and  divide  the  four-cycle 
engine  into  a  number  of  classes.  For  instance, 
if  the  valves  controlling  the  admission  of  the 
explosive  mixture  are  placed  on  one  side  of  the 
cylinders  and  those  officiating  over  the  exit  of 
the  exhaust  gases  are  located  on  the  opposite 
side,  the  motor  is  known  as  the  "  T-head  "  type 
because  of  the  shape  of  its  cylinders. 

All  valves  that  are  placed  at  the  side  of  the 
cylinder  must  operate  in  pockets  so  as  not  to  in- 
terfere with  the  movement  of  the  piston. 
These  pockets  are  cast  with  the  cylinder  and 
form  a  projection  at  its  side  near  the  top. 
When  these  projections  are  cast  on  opposite 
sides,  a  cylinder  having  the  shape  of  the  letter 
"  T "  is  formed,  while  if  the  valves  operate 
on  the  same  side,  the  single  projection  forms 
a  cylinder  having  the  shape  of  the  inverted 


TYPES  OF  MOTOR  17 

letter  u  L."  Hence  cylinders  having  valves  on 
opposite  sides  are  called  "  T  "-head  motors, 
while  "  L  "-head  motor  is  synonymous  for  an 
engine  having  "  valves  on  the  same  side/' 

When  the  valves  are  placed  in  the  head, 
there  is  no  need  of  separate  pockets,  for  these 
valves  operate  from  above  and  do  not  inter- 
fere with  the  movement  of  the  piston.  There 
may  be  a  combination  of  these  positions,  one 
set  of  valves  being  placed  in  the  head  and  the 
others  at  the  side.  This  is  known  as  the  "  in- 
let in  head,  exhaust  at  side"  type — or  vice 
versa,  as  the  case  may  be. 

The  valve  that  has  been  in  almost  universal 
use  in  motor  cars  is  known  as  the  "  poppet " 
type,  as  distinguished  from  the  sliding  and 
rotary  styles.  As  evidenced  by  its  name,  the 
poppet  valve  is  pushed  or  lifted  from  its  seat, 
and  thus  the  full  area  of  the  opening  to  the  pas- 
sage is  made  available  almost  immediately. 
The  poppet  valve  is  lifted  by  a  cam,  the  shape 
of  which  determines  the  relative  speed  of 
operation  of  the  valve,  and  is  returned  to  its 
seat  by  a  stiff  spring.  The  nature  of  the  con- 
tact that  the  valve  makes  with  its  seat  depends 
upon  the  condition  of  the  surfaces  and  is  the 
deciding  factor  as  to  whether  the  joint  is  com- 
pletely air-tight  or  not. 


18      THE  GASOLINE  MOTOR 

When  the  exhaust  valve  is  opened,  its  head 
is  thrust  directly  in  the  path  of  the  hot,  out- 
rushing  gases;  these  same  gases  also  swirl 
around  the  edge  of  the  seat.  The  excessive 
heat  and  the  particles  of  carbon  that  are  often 
found  in  the  exhaust  gases  tend  to  corrode  and 
build  a  deposit  on  the  edges  of  the  valve  and 
its  seat,  thus  eventually  preventing  perfect  con- 
tact from  taking  place.  This  makes  necessary 
the  grinding  of  the  valves — an  operation  that 
is  familiar  to  the  majority  of  motor  car  owners 
and  drivers. 

While  the  poppet  valve  motor  is  still  used 
on  the  majority  of  automobiles,  a  new  and 
radical  type  of  valve  mechanism  has  been  giv- 
ing successful  results.  This  is  known  as  the 
sliding  sleeve  type  of  motor,  and  while  it  has 
been  used  for  several  seasons  in  Europe,  1912 
saw  its  adoption  for  the  first  time  in  America. 
The  sleeve  motor,  it  must  be  understood,  is  of 
the  four-cycle  type,  the  events  occurring  in  the 
same  order  as  on  any  ordinary  automobile  mo- 
tor, and  the  only  difference  lies  in  the  nature 
of  the  valves  that  control  the  openings  of  the 
exhaust  and  inlet  passages.  That  this  differ- 
ence is  great,  however,  will  be  realized  when 
it  is  understood  that  the  valves  consist  of  two 
concentric  shells,  in  the  inner  one  of  which  the 


TYPES  OF  MOTOR  19 

piston  reciprocates.  In  other  words,  two  hol- 
low cylinders  line  the  interior  of  the  cylinder 
casting  and  replace  the  poppet  valves  and 
pockets  of  the  more  familiar  type  of  motor. 

These  sleeves,  or  shells,  or  hollow  cylinders 
— or  whatever  name  it  is  chosen  to  give  them — 
slide  up  and  down  in  the  same  line  of  action 
as  that  of  the  piston.  A  port,  or  slot,  is  cut 
near  the  top  on  opposite  sides  of  each  of  the 
shells.  These  four  ports  are  so  arranged  that 
one  set  opens  directly  opposite  the  intake  pas- 
sage, while  the  other  opens  by  the  exhaust 
manifold  entrance.  When  it  is  said  that  these 
ports  open,  it  is  meant  that  similar  slots  in  the 
two  sleeves  come  opposite  each  other,  or 
"  register,"  so  that  an  unobstructed  passage  for 
the  gas  is  offered.  The  port  in  one  sleeve  may 
be  opposite  the  intake  pipe  entrance,  but  if 
the  slot  in  the  other  sleeve  does  not  correspond 
with  this,  the  passage  is  effectively  closed. 

Thus  it  will  be  seen  that  the  ports  are  opened 
and  closed  by  the  movement  of  the  sleeves  in 
opposite  directions.  For  example,  just  before 
the  opening  of  the  intake  port,  the  inner  sleeves 
will  be  traveling  upward  while  the  outer  shell 
moves  downward,  and  the  slots  in  the  two 
shells  will  be  opposite  each  other  at  the  instant 
that  they  pass  the  inlet  pipe.  This  give  a  much 


20      THE  GASOLINE  MOTOR 

quicker  opening  than  would  be  the  case  if  one 
shell  stood  still  while  the  other  moved  down- 
ward, and  it  is  because  the  slots  approach  each 
other  from  opposite  directions  that  this  motor 
can  be  run  efficiently  at  high  speeds. 

Inasmuch  as  this  is  a  four-cycle  motor  and 
the  explosions  occur  in  each  cylinder  but  once 
during  every  two  revolutions  of  the  flywheel, 
each  sleeve  makes  but  one  stroke  for  every  two 
of  the  piston.  The  sleeves  are  operated  by 
eccentrics  attached  to  a  shaft  driven  at  a  two- 
to-one  speed  by  the  crank  shaft  of  the  motor, 
and  as  they  are  well  lubricated  there  is  but  very 
little  friction  generated  between  them  and  the 
piston.  In  fact,  it  has  been  shown  that  the 
power  required  to  operate  the  sleeves,  when 
well  lubricated,  is  considerably  less  than  that 
consumed  by  the  springs  and  valve  mechanism 
of  the  poppet  valve  motor,  for  the  reason  that 
the  former  type  of  valve  does  not  open  against 
the  pressure  of  the  exhaust,  as  is  the  case  with 
the  ordinary  gas  engine  valve. 

Besides  the  two-  and  four-cycle  divisions,  a 
motor  is  known  by  the  arrangement  of  its 
cylinders  and  is  classified  as  "  cylinders  cast 
separately,"  "  cast  in  pairs,"  or  "  triple  cast," 
according  to  whether  there  are  one,  two  or 
three  cylinders  to  a  unit.  The  last-named  type 


TYPES  OF  MOTOR  21 

is  not  as  common  as  are  the  "  pair-cast "  cylin- 
ders and  of  course  can  only  be  used  on  six- 
cylinder  motors. 

When  all  of  the  cylinders  of  a  motor  are 
cast  in  one  piece,  the  engine  is  known  as  a 
"  bloc  "  motor.  This  is  a  type  that  has  come 
into  popular  use  for  small  and  medium-sized 
power  plants  during  the  past  few  years  on  ac- 
count of  the  simplicity  of  its  construction  and 
the  smooth  and  compact  design  that  is  rendered 
possible.  Of  course  it  may  be  argued  that,  with 
such  a  design,  the  entire  set  must  be  replaced 
if  a  single  cylinder  is  damaged,  but  castings 
have  been  so  improved  that  an  accident  or  im- 
perfection requiring  the  renewal  of  a  cylinder 
is  very  rare. 

It  is  evident  that,  beyond  a  certain  size  of 
cylinder,  a  bloc  casting  becomes  too  bulky  to  be 
handled  conveniently,  and  as  the  entire  casting 
must  be  removed  when  it  is  desired  to  reach 
the  connecting  rods,  crank  shaft,  or  piston 
rings,  a  motor  so  designed  will  seldom  be  found 
that  develops  more  than  forty  or  fifty  horse- 
power. This  type  of  casting  is  found  on  some 
six-cylinder  cars,  however,  but  it  is  naturally 
only  the  "  light  sixes  "  that  will  use  such  a  mo- 
tor. 

Above  six-cylinders,  a  motor  is  usually  ar- 


22      THE  GASOLINE  MOTOR 

ranged  with  its  power  units  set  at  an  angle  on 
either  side  of  the  vertical,  thus  forming  the 
V-shaped  motor.  Several  eight-cylinder  mo- 
tors are  so  constructed,  the  units  being  arranged 
four  on  a  side  and  each  set  placed  at  an  angle 
of  about  thirty  degrees  from  the  vertical.  This 
gives  the  effect  of  two  four-cylinder  motors 
placed  side  by  side  and  operating  on  the  same 
crank  shaft. 

In  order  to  make  the  motor  as  compact  as 
possible,  the  cylinders  are  "  staggered;"  or,  in 
other  words,  the  cylinders  of  one  set  are  placed 
opposite  the  spaces  between  the  units  of  the 
other.  It  will  be  seen  that  the  V-shaped  design 
of  motor  shortens  the  power  plant  and  enables 
it  to  be  set  in  a  much  smaller  space  under  the 
bonnet  than  would  be  the  case  were  the  cylin- 
ders placed  one  in  front  of  the  other,  as  in  the 
four-  and  six-cylinder  types. 

As  a  rule,  the  two-cylinder,  four-cycle  motor 
is  of  a  different  type  from  its  four-  and  six- 
cylinder  cousins,  and  is  known  as  a  "  hori- 
zontal opposed  "  engine.  In  such  a  motor,  the 
cylinders  are  set  lengthwise  and  the  pistons 
operate  opposite  each  other  in  such  a  manner 
that  a  "long,  narrow,  and  thin"  power  plant 
is  obtained  that  is  especially  well-suited  for  a 
location  under  the  body  of  the  car.  In  fact, 


TYPES  OF  MOTOR  23 

this  horizontal  motor,  which  may,  of  course,  be 
of  the  four-cylinder  type,  is  the  only  shape  that 
can  well  be  used  under  the  body  or  seat  of  a 
touring  car.  In  some  small  runabouts,  how- 
ever, the  "  double-opposed  "  motor  is  used  to 
good  advantage  under  the  forward  bonnet,  as 
in  the  "  big  fellows." 

There  are,  of  course,  many  other  features  of 
design  that  serve  to  differentiate  one  automo- 
bile power  plant  from  another,  but  these  are 
details  that  do  not  serve  to  classify  the  motor, 
and  the  man  who  knows  whether  his  machine 
is  two-  or  four-cycle;  poppet  or  sleeve  valve; 
separate,  pair,  or  en  bloc  cylinder  castings; 
and  "  T  "-  or  "  L  "-head  shape  will  have  at  his 
fingers'  ends  distinctions  that  would  have 
"  floored"  the  salesman  of  a  few  years  ago. 


CHAPTER  II 

VALVES 

IT  has  been  stated  in  the  preceding  chapter 
that  the  valves  of  the  gasoline  motor  are 
the  sentinels  placed  on  guard  at  the  en- 
trance to  and  exit  from  each  cylinder  to  make 
certain   that   the   mixture   follows   its   proper 
course  at  the  proper  time. 

Therefore,  if  we  accept  the  definition  that  a 
valve  is  a  mechanical  appliance  for  controlling 
the  flow  of  a  liquid  or  a  gas,  strictly  speaking 
no  such  thing  as  a  "valveless"  motor  exists. 
Two-cycle  motors  are  sometimes  said  to  be 
valveless  because  of  the  fact  that  the  move- 
ment of  the  piston  automatically  regulates  the 
flow  of  the  exhaust  and  intake  gases,  but  in  this 
case  the  piston  is  in  reality  the  valve.  On  the 
four-cycle  motor,  however,  like  events  take 
place  only  on  alternate  strokes  in  the  same  di- 
rection, and  consequently  some  controlling 
mechanism  that  operates  but  once  for  every 

24 


VALVES  25 

four  strokes  of  the  piston  is  needed  to  time  the 
flow  of  the  gases. 

As  has  been  stated  in  the  previous  chapter, 
the  most  common  form  of  valve  is  known  as 
the  poppet  type  from  the  fact  that  its  action 
is  a  lifting  one.  Such  a  valve  may  be  located 
in  a  projection  cast  on  either  side  of  the  top 
of  each  cylinder,  or  it  may  be  inverted  from 
this  position  and  placed  in  the  cylinder  head. 
When  in  the  former  location,  the  valve  is 
opened  by  an  upward  push  on  the  rod  to  which 
it  is  attached  at  its  center,  while  a  valve  placed 
in  the  cylinder  head  is  forced  down  to  allow 
the  escape  or  entrance  of  the  exhaust  or  intake 
gases.  The  ordinary  type  of  poppet  valve  is 
somewhat  similar  in  shape  to  a  mushroom, 
having  a  very  thin  and  flat  head  and  a  slender 
stem.  The  disc  portion  of  the  valve  is  known 
as  its  head,  while  the  rod  forged  with  the  valve 
and  by  which  the  head  is  raised  and  lowered 
is  called  the  stem. 

The  projections  cast  in  the  cylinders  of  a 
"  T  "-head  or  "  L  "-head  motor,  and  in  which 
the  valves  are  placed,  are  known  as  the  valve 
pockets.  Valves  so  located  are  lifted  by  a  di- 
rect upward  push  caused  by  the  rotation  of  a 
cam  and  are  returned  to  their  closed  position 
by  means  of  the  extension  of  a  stiff  spiral 


26      THE  GASOLINE  MOTOR 

spring  surrounding  each  valve  stem.  It  is  only 
the  outer  edge  of  the  lower  side  of  the  valve 
head  that  comes  in  contact  with  the  surround- 
ing surfaces  of  the  opening  which  is  closed 
when  the  valve  is  returned  to  its  ordinary  posi- 
tion by  the  spring. 

This  surface  of  contact  surrounding  the 
opening  is  known  as  the  valve  seat,  and  it  is 
this,  together  with  the  edge  of  the  valve  which 
rests  against  it,  that  must  be  ground  smooth 
in  order  to  insure  a  tight  joint  when  the  valve 
is  closed.  On  the  majority  of  poppet  valves 
the  edge  of  the  head  and  the  seat  against  which 
it  rests  are  beveled  to  an  angle  of  approxi- 
mately forty  degrees  in  order  to  conform  to 
the  natural  direction  taken  by  the  gases  when 
they  are  admitted  or  expelled.  In  a  few  cases, 
however,  the  seat  angle  is  ninety  degrees,  which 
means  that  the  edge  of  the  head  is  ground  flat, 
or  straight,  at  right  angles  to  the  stem. 

One  of  the  chief  advantages  found  in  the 
use  of  a  poppet  valve  is  the  fact  that  a  large 
opening  can  be  obtained  after  the  valve  head 
has  been  raised  but  a  comparatively  short  dis- 
tance. This  means  that  the  valve  stem  need 
travel  only  a  fraction  of  an  inch  between  the 
full  open  and  the  full  closed  position  of  the 
valve  and  that  the  operating  mechanism  for 


VALVES  27 

obtaining  this  lift  is  simple.  Practically  every 
poppet  valve,  therefore,  is  lifted  by  means  of 
a  cam,  which  is  a  thick,  irregularly-shaped 
piece  of  steel  mounted  on  a  shaft  known  as 
the  cam  shaft.  If  the  end  of  the  valve  stem, 
or  a  rod  connected  to  it,  is  held  against  the 
periphery  of  the  cam  while  the  latter  is  re- 
volved by  its  shaft,  the  valve  will  be  forced  up, 
or  away,  rather,  an  amount  corresponding  to 
the  increase  in  distance  between  the  periphery 
of  the  cam  at  this  point  of  contact  and  its 
axis. 

In  other  words,  if  the  cam  were  a  true  circle 
with  its  axis  passing  through  its  center,  there 
would  be  no  motion  of  the  valve,  for  all  points 
of  the  periphery  of  a  circle  are  at  the  same  dis- 
tance from  the  center.  Consequently  a  portion 
of  the  periphery  of  the  cam  is  extended  in  the 
shape  of  a  "nose,"  the  projection  of  this  be- 
yond the  smallest  diameter  of  the  cam  being 
the  distance  that  the  valve  will  be  lifted  when 
this  point  of  the  cam  surface  comes  in  contact 
with  the  stem  or  push  rod.  The  broader, 
or  more  blunt,  the  nose  of  the  cam, 
the  longer  will  the  valve  remain  open 
as  the  cam  shaft  is  revolved,  while  the 
"  slope "  of  the  sides  of  the  nose  deter- 
mines the  rapidity  with  which  the  valve  will  be 


28      THE  GASOLINE  MOTOR 

pushed  out  and  back.  Inasmuch  as  the  valve 
should  remain  closed  throughout  two-thirds  or 
three-quarters  of  every  two  revolutions  of  the 
flywheel,  the  greater  part  of  the  periphery  of 
the  cam  is  circular,  or  at  the  same  distance 
from  the  axis  at  all  points. 

As  has  been  mentioned  before,  the  cam 
serves  only  to  lift  the  valve,  the  return  of  the 
latter  to  its  seat  being  obtained  by  the  force 
from  a  spring  that  is  coiled  around  the  stem. 
Thus  the  spring  holds  the  end  of  the  push  rod 
at  all  times  against  the  periphery  of  the  cam. 
This  push  rod,  in  some  instances,  is  a  small 
bar  of  special  steel  that  slides  in  guides  of  long- 
wearing  bearing  alloy.  The  upper  end  of  the 
push  rod  is  in  contact  with  the  lower  end  of 
the  valve  stem,  while  its  other  extremity  is  of- 
tentimes designed  in  the  form  of  a  small  steel 
roller  that  thus  serves  to  create  a  rolling  con- 
tact with  the  periphery  of  the  cam. 

In  other  designs,  the  lower  extremity  of  the 
push  rod  may  be  in  the  form  of  a  specially- 
hardened  steel  pin  with  a  rounded  end,  while 
still  a  third  type  consists  of  a  flat  disc  slightly 
"  offset "  on  the  end  of  the  push  rod  so  that 
various  points  of  its  surface  will  come  in  con- 
tact with  the  periphery  of  the  cam  and  the 
wear  will  be  evenly  distributed.  Whatever  the 


VALVES  29 

particular  design,  however,  the  cam  is  well 
lubricated  and  both  it  and  the  push  rod  are 
intended  to  last  as  long  as  any  part  of  the  mo- 
tor. 

Many  motors  are  designed  with  one  valve  at 
the  side  and  the  other,  usually  the  intake,  in 
the  head.  There  are  also  many  motors  manu- 
factured that  have  both  the  intake  and  the  ex- 
haust valves  located  in  the  head,  in  which  case 
.the  valve  pockets,  or  projections,  are  elim- 
inated. Such  valves  may  be  operated  by  the 
same  type  of  cams  and  cam  shaft  as  those  used 
to  open  the  valves  at  the  side.  As  the  opening 
of  a  valve  located  in  the  head  is  downward, 
however,  the  motion  produced  by  the  cam  on 
the  push  rod  must  be  reversed  in  direction. 
This  reversal  of  motion  is  obtained  by  means 
of  a  lever  mounted  at  its  center  and  placed  in 
contact  with  the  upper  extremity  of  the  push 
rod  at  its  outer  end.  The  other  end  of  this 
lever  operates  in  contact  with  the  end  of  the 
valve  stem,  and  thus  an  upward  push  on  the 
rod  is  converted  into  a  downward  thrust  on  the 
stem.  This  lever  that  reverses  the  direction  of 
the  push  rod  motion  is  known  as  a  rocker  arm 
and  is  mounted  in  a  yoke  cast  with  the  cylinder 
head. 

Inasmuch  as  a  spring  is  used  to  keep  the 


30      THE  GASOLINE  MOTOR 

valve  tightly  closed  when  the  cam  is  not  lifting 
the  latter,  it  is  the  contact  of  the  valve  head 
with  its  seat  that  must  form  the  stop  to  the 
motion  of  the  spring.  It  will  be  seen  that  the 
force  of  the  spring  is  communicated  through 
the  valve  stem  to  the  push  rod,  and  thence  to 
the  periphery  of  the  cam  when  the  latter  is  in 
a  position  to  lift  the  valve.  The  push  rod 
should  not  be  forced  tightly  against  the  periph- 
ery of  the  cam  when  the  valve  is  closed,  how- 
ever, for  this  would  prevent  perfect  contact 
between  the  valve  and  its  seat.  Consequently 
there  should  be  a  certain  amount  of  "play" 
between  the  end  of  the  push  rod  and  valve  stem 
so  that  it  will  be  certain  that  the  head  is  forced 
against  the  seat  with  the  full  power  of  the 
spring  and  without  the  cam  serving  as  a  stop. 
On  the  other  hand,  this  play  should  not  be 
too  great,  for  the  cam  and  push  rod  will  then 
move  an  appreciable  distance  before  the  valve 
is  raised.  This  will  cause  the  opening  of  the 
valve  to  occur  late  and  will  reduce  the  distance 
that  the  stem  is  raised,  thus  restricting  the  size 
of  the  opening.  Furthermore,  an  undue 
amount  of  play  between  the  ends  of  the  push 
rod  and  stem  will  result  in  a  pound  or  "  ham- 
mer blow  "  between  the  two  that  is  liable  to 
wear  the  surfaces  rapidly. 


VALVES  31 

The  "  happy  medium  "  that  will  give  the 
best  results  may  be  obtained  by  properly  set- 
ting the  small  valve  "  tappets  "  that  are  se- 
cured to  the  end  of  the  stems  or  push  rods. 
By  turning  the  nut  of  the  tappet  in  one  direc- 
tion, the  length  of  the  push  rod  will  be  re- 
duced, while  the  reverse  operation  will  in- 
crease the  length  of  the  rod  or  stem.  This  is 
primarily  intended  for  taking  up  any  wear  that 
may  occur  at  the  ends  of  the  push  rod  or  valve 
stem.  In  the  case  of  engines  having  the  valves 
in  the  head,  the  long  push  rod  of  each  valve 
should  be  so  loose  as  to  move  perceptibly  when 
shoved  up  and  down  by  the  thumb  and  finger. 

When  the  rocker  arm  is  pressed  down 
•against  the  valve  stem,  the  space  between  the 
other  end  of  the  rocker  arm  and  the  push  rod 
should  be  sufficiently  wide  to  admit  a  piece  of 
tissue  paper.  The  same  test  may  be  made  in 
connection  with  valves  located  at  the  side,  af- 
ter first  ascertaining  that  the  end  of  the  short 
push  rod  is  resting  firmly  against  the  periph- 
ery of  the  cam.  The  play  will  be  apparent, 
of  course,  only  when  the  valve  is  tightly  closed, 
and  in  order  to  make  certain  that  their  cams 
are  in  the  "  inactive "  position,  the  piston 
should  be  set  at  the  beginning  of  the  explosion 
stroke  when  testing  the  intake  or  exhaust  valve. 


32      THE  GASOLINE  MOTOR 

This  is  at  the  point  of  ignition  and  is  the  time 
at  which  both  valves  should  be  tightly  closed. 

TEe  cam  shaft  to  which  the  cams  that  oper- 
ate the  valves  are  attached  is  generally  placed 
inside  the  crank  case.  If  the  motor  is  of  the 
"  T  "-head  type,  having  valves  on  opposite 
sides  of  the  cylinders,  the  cam  shaft  operating 
the  exhaust  valves  will  be  found  on  one  side  of 
the  crank  case,  while  that  for  opening  the  in- 
let valves  will  be  located  on  the  other.  If  the 
motor  is  of  the  "  L  "-head  type,  all  the  cams 
will  be  placed  on  the  one  shaft.  The  cams  are 
sometimes  forged  with  their  shaft  in  a  solid 
piece,  while  in  other  designs  they  are  keyed  in 
place,  but  whatever  type  is  used,  the  cams  and 
their  shaft  may  be  considered  as  integral  with 
each  other. 

The  cam  shafts  are  generally  driven  by  a 
gear  meshing  with  a  smaller  one  attached  to 
the  front  end  of  the  crank  shaft  of  the  motor, 
which  forms  one  of  the  forward  train  of  gears 
that  are  enclosed  in  an  aluminum  case.  If  the 
cam  shaft  is  driven  at  the  same  speed  as  is  the 
crank  shaft  of  the  motor,  it  will  be  seen  that 
the  valves  will  open  once  at  every  revolution 
of  the  flywheel.  In  a  four-cycle  motor,  how- 
ever, the  explosion  and  other  events  occur  but 
once  in  each  cylinder  for  every  two  revolutions 


VALVES  33 

of  the  flywheel,  and  consequently  the  cam  shaft 
must  be  driven  at  one-half  the  speed  of  the 
crank  shaft. 

To  obtain  the  proper  speed  ratio,  each  cam 
shaft  is  driven  by  a  "  two-to-one"  gear,  which 
means  that  the  gear  on  the  end  of  the  crank 
shaft  has  but  one-half  as  many  teeth  as  have 
those  attached  to  the  cam  shafts.  There  is 
thus  one  revolution  of  each  cam  shaft  gear 
for  every  two  of  the  crank  shaft  gear,  and  con- 
sequently each  cam  shaft  is  driven  at  the  re- 
quired half  speed. 

The  cam  shafts  may  be  driven  by  a  chain, 
the  links  of  which  fit  over  teeth  cut  on  sprocket 
wheels,  but  there  must  always  be  a  constant 
relation  between  the  position  of  the  cam  shaft 
and  that  of  the  crank  shaft.  This  constant 
relation  is  necessary  in  order  that  the  valves 
will  open  and  close  at  the  proper  points  dur- 
ing the  travel  of  the  piston.  For  example,  the 
exhaust  valve  should  open  toward  the  end  of 
the  explosion  stroke  in  order  to  allow  the 
burned  gases  to  be  forced  out,  and  the  cam  for 
operating  this  valve  should  always  be  in  the 
lifting  position  at  exactly  the  proper  moment. 

If  the  cam  shaft  is  not  positively  driven,  this 
position  may  change  and  the  exhaust  valve 
might  be  opened  at  the  beginning  of  the  igni- 


34      THE  GASOLINE  MOTOR 

tion  of  the  charge,  in  which  case  the  force  of 
the  explosion  would  be  wasted  almost  entirely. 
On  the  other  hand,  the  inlet  valve  should  open 
at  about  the  beginning  of  the  suction  stroke  in 
order  that  the  fresh  charge  may  be  drawn  in  by 
the  downward  travel  of  the  piston;  it  is  evi- 
dent that  this  cannot  be  opened  at  any  other 
time  without  a  resulting  loss  in  the  power  de- 
veloped by  the  motor. 

The  proper  timing  of  the  action  of  the 
valves  is  consequently  one  of  the  most  import- 
ant adjustments  of  a  motor.  When  the  motor 
is  assembled  and  tested  at  the  factory,  the 
valves  are  properly  timed  and  there  is  no  possi- 
bility that  they  will  require  further  adjustment 
in  this  respect  until  after  the  engine  is  "  taken 
down  "  for  the  purpose  of  cleanning  or  the  re- 
newal of  a  broken  part.  If  it  should  ever  be- 
come necessary  to  remove  one  of  the  cam 
shafts  or  any  of  the  gears  constituting  the  for- 
ward train,  the  greatest  care  should  be  taken  to 
make  certain  that  all  are  returned  to  exactly 
their  original  position.  A  difference  of  one 
tooth  in  the  relative  meshing  of  the  gears  may 
result  in  a  loss  of  fifty  per  cent,  of  the  power 
developed  by  the  motor. 

Absolute  rules  for  the  proper  timing  of  the 
valves  cannot  be  given  here,  for  various  mo- 


VALVES  35 

tors  are  designed  with  slightly  different  posi- 
tions at  which  the  exhaust  and  inlet  valves 
should  be  opened  and  closed.  A  cam  shaft 
should  never  be  removed,  however,  without 
first  marking  the  intermeshing  teeth  of  its  driv- 
ing gear  and  those  of  its  companions.  This 
may  best  be  done  by  means  of  a  small  prick 
punch  which,  when  tapped  lightly  with  a  ham- 
mer, will  make  a  permanent  mark  at  the  de- 
sired point  on  the  surface  of  the  gear.  If  the 
motor  is  of  the  "  T  "-head  type,  having  its 
valves  operated  by  two  cam  shafts,  care  should 
be  taken  to  designate  the  right  and  left-hand 
gears  so  that  their  positions  will  not  be  re- 
versed if  both  have  been  removed  at  the  same 
time. 

A  safe  method  to  pursue  is  to  indicate  the 
right-hand  gear  with  one  punch  mark,  while 
two  should  be  used  for  the  gear  at  the  left. 
Three  teeth  should  be  marked  on  each  pair 
of  intermeshing  gears.  That  is,  a  tooth  on  one 
gear  should  be  marked,  and  then  each  of  the 
teeth  between  which  it  meshes  on  the  other 
gear.  The  second  cam  shaft  gear  should  be 
marked  before  the  motor  is  turned. 

As  has  been  stated,  the  cams  on  many  mo- 
tors are  forged  integral  with  their  shafts,  and 
there  is  consequently  no  possibility  of  the  re- 


36      THE  GASOLINE  MOTOR 

moval  of  one  from  the  other.  Those  cams 
which  are  keyed  to  their  shafts  are  accurately 
and  rigidly  set  and  the  keyways  so  cut  that 
there  is  slight  chance  of  a  mistake  in  returning 
a  cam  that  has  been  removed.  It  should 
seldom  be  necessary  to  remove  a  cam  from  its 
shaft,  however. 

Many  motors  are  provided  with  timing 
marks  on  the  flywheel  to  indicate  the  positions 
of  the  latter  at  which  the  valves  of  the  various 
cylinders  should  open  and  close.  In  connection 
with  these  marks  a  pointer  attached  to  the 
crank  case  and  indicating  the  top  of  the  fly- 
wheel is  used.  When  the  line  on  the  flywheel 
marked,  for  example,  4  Ex  o,  is  under  the 
pointer,  it  indicates  that  the  exhaust  valve  on 
the  fourth  cylinder  should  be  about  to  open. 
If  the  motor  is  turned  but  very  little  beyond 
this  point,  a  lifting  should  be  felt  at  the  proper 
push  rod  or  valve  stem. 

It  is  well  to  test  the  setting  of  the  valves  oc- 
casionally by  means  of  these  marks,  for  wear 
at  the  rocker  arms,  the  push  rods,  the  valve 
stem,  or  the  cam  travelers  will  result  in  un- 
evenly-timed valves.  It  should  be  remembered 
that  it  is  the  valve  itself  that  should  open  after 
the  proper  mark  on  the  flywheel  has  been 
passed,  and  that  the  movement  of  a  long  push 


VALVES  37 

rod  is  not  sufficient  evidence  that  the  valve  is 
beginning  to  leave  its  seat.  There  may  be  so 
great  an  amount  of  lost  motion  between  the 
push  rod,  cam,  rocker  arm,  and  valve  stem  that 
the  flywheel  may  be  turned  several  degrees  be- 
yond the  proper  point  before  this  "  play  "  will 
be  taken  up  and  the  valve  itself  will  begin  to 
move. 

Although  the  timing  of  a  motor  may  be 
given  in  inches  of  piston  travel  beyond  a  cer- 
tain dead  center,  at  which  point  an  exhaust  or 
inlet  valve  should  open  or  close,  it  is  generally 
expressed  in  degrees  of  flywheel  revolution. 
Suppose,  for  example,  it  is  said  that  the  inlet 
valve  should  open  ten  degrees  after  the  begin- 
ning of  the  suction  stroke.  This  would  indicate 
that  the  flywheel  should  be  turned  through  an 
arc  of  ten  degrees  from  the  point  at  which  the 
piston  is  at  its  upper  dead  center  before  the 
inlet  valve  for  that  particular  cylinder  should 
begin  to  open.  Expressed  in  terms  of  fly- 
wheel revolution,  the  total  travel  of  the  piston 
during  each  stroke  is  180  degrees,  and  as  in 
the  proximity  of  its  dead  centers  the  piston 
moves  but  a  short  distance  in  comparison  with 
the  size  of  the  arc  through  which  the  flywheel 
swings,  valves  may  be  set  very  accurately  by 
this  method. 


38      THE  GASOLINE  MOTOR 

Not  all  cam  shafts  for  operating  the  valves 
are  located  in  the  crank  case.  On  several  de- 
signs of  motors  the  cam  shaft  extends  along 
the  top  of  the  cylinders  and  is  driven  by  a  verti- 
cal shaft  and  two  sets  of  bevel  gears.  On 
such  motors  both  inlet  and  exhaust  valves  are 
located  in  the  cylinder  heads,  and  owing  to  the 
proximity  of  the  cam  shaft,  but  short  push  rods 
and  valve  stems  are  needed.  The  valves  are 
sometimes  operated  by  means  of  a  bell  crank 
or  rocker  arm  that  acts  directly  against  the 
cam  surface  and  end  of  the  valve  stem. 

On  some  designs  a  double  cam  is  used  which 
serves  to  operate  both  the  inlet  and  exhaust 
valves  of  the  cylinder.  The  bearings  and  cams 
of  such  a  shaft  are  generally  enclosed  in  oil  and 
dustproof  casing  screwed  to  the  top  of  the 
cylinders.  Such  a  cam  shaft  should  never  be 
dismounted  without  first  marking  intermeshing 
teeth  of  all  spur  and  bevel  gears  that  are  con- 
cerned in  its  operation. 

All  poppet  valves  must  be  accessible  an'd 
readily  removable  for  the  purpose  of  cleaning 
and  grinding  the  contact  surfaces  of  the  head 
and  seat.  The  pockets  in  which  the  valves 
placed  at  the  side  of  a  cylinder  are  located  are 
generally  provided  with  large  screw  plugs  at 
the  top.  Such  a  plug  may  be  removed  with  a 


VALVES  39 

heavy  wrench,  and  as  the  opening  which  it 
fills  is  larger  than  the  head  of  the  valve,  the 
latter  may  be  removed  after  first  loosening  the 
spiral  spring  surrounding  its  stem.  It  is  not 
necessary  to  remove  the  valve  entirely  from  its 
pocket  in  order  to  grind  its  surfaces,  but  the 
pin  holding  the  spring  stop  in  place  must  be 
withdrawn  so  that  the  tension  of  the  spring  on 
the  valve  will  not  be  so  great  as  fro  prevent 
the  latter  from  being  lifted  to  permit  the  intro- 
duction of  the  abrasive  and  turning  the  head 
with  the  grinding  tool. 

Valves  located  in  the  head  of  the  cylinder 
must  be  removed  entirely  before  their  surfaces 
can  be  ground.  This,  however,  is  not  a  dif- 
ficult operation,  as  the  valve  and  its  seat  are 
generally  placed  in  a  removable  "  cage  "  that 
either  screws  in  place  or  is  held  firmly  in  posi- 
tion by  means  of  a  clamp  or  like  device.  In- 
asmuch as  the  seat  is  contained  in  this  remova- 
ble cage  in  which  the  valve  operates,  the  grind- 
ing may  be  done  at  a  work  bench  or  on  the  bed 
of  any  convenient  tool,  independently  of  the 
location  of  the  motor. 

If  a  valve  seems  sluggish  in  its  action  at 
high  speeds  of  the  motor,  it  is  possible  that  its 
spring  has  become  somewhat  weakened. 
These  springs  are  designed  to  be  exceedingly 


40      THE  GASOLINE  MOTOR 

stiff  and  heavy,  some  of  them  requiring  a  pres- 
sure of  two  hundred  and  fifty  pounds  to  com- 
press the  coils  one  inch.  With  such  a  spring, 
a  special  tool  is  required  to  compress  it  suf- 
ficiently to  enable  the  valve  to  be  removed.  A 
spiral  spring  that  has  become  weakened  may 
sometimes  be  strengthened  by  "  stretching," 
but  it  is  not  to  be  supposed  that  this  would  be 
of  great  avail  in  the  case  of  a  spring  as  heavy 
as  those  used  on  some  valves.  If,  however,  a 
flat  tool  is  introduced  between  the  various  coils 
and  each  is  separated  slightly  so  that  the  ulti- 
mate length  of  the  entire  spring  is  greater  than 
it  was  formerly,  it  will  exert  a  more  powerful 
force  on  the  valve  when  it  is  returned  to  its 
place  surrounding  the  stem. 

Stiffening  the  spring,  however,  will  be  of  but 
little  help  if  the  stem  or  push  rod  is  tight  in 
the  guides  through  which  it  slides.  These 
guides  -are  often  made  of  a  special  bearing 
bronze  and  are  designed  to  withstand  a  large 
amount  of  wear,  but  the  friction  surfaces  must 
be  lubricated  if  satisfactory  service  is  to  be  ob- 
tained. The  lower  guide  is  generally  lubri- 
cated by  the  oil  from  the  cams,  while  the  guide 
near  the  valve  may  receive  its  oil  from  the  en- 
gine cylinder.  It  is  not  necessary  that  these 
guides  shall  be  packed  or  that  they  shall  be  par- 


VALVES  41 

ticularly  tight,  as  they  are  not  called  upon  to 
retain  any  gas  or  air  pressure,  but  they  must 
hold  the  stem  and  rod  sufficiently  rigid  to  pre- 
vent any  perceptible  side  motion  and  thus  cause 
imperfect  seating  of  the  valve.  In  replacing 
valve  stems  and  push  rods,  it  should  be  made 
certain  that  each  works  freely  in  its  guide  be- 
fore the  spring  is  installed.  If  there  is  a  slight 
tendency  for  the  guide  to  grip  the  rod  or  stem, 
the  latter  should  be  smoothed  with  emery 
paper  at  the  point  at  which  it  comes  in  contact 
with  the  guide  and  plenty  of  oil  applied  until 
the  surfaces  are  well  "  worked  down."  As  the 
distance  that  the  rods  and  stems  travel  through 
the  guides  is  comparatively  short,  the  wear  is 
slight  and  only  a  small  amount  of  lubricant  is 
needed,  provided  the  rubbing  surfaces  are 
smooth  and  well-fitted  to  each  other. 

The  mechanism  of  a  sleeve  valve  motor  is 
slightly  different  from  that  of  the  poppet  valve 
type.  Each  sleeve  is  operated  by  a  connecting 
rod  and  eccentric  mounted  on  a  shaft  driven 
by  a  chain  or  gears  from  the  crank  shaft  of  the 
motor.  The  eccentric  replaces  the  cams  of  the 
poppet  valve  motor,  and  as  it  must  maintain  a 
certain  relation  with  the  position  of  the  piston 
in  order  that  the  operation  of  the  valves  shall 
be  timed  correctly,  the  same  care  must  be  ob- 


42      THE  GASOLINE  MOTOR 

served  in  replacing  the  eccentric  shaft  with  the 
proper  teeth  of  the  sprocket  or  gear  in  mesh 
as  has  already  been  described  in  connection 
with  the  cam  shaft  of  the  poppet  valve  motor. 


CHAPTER  III 

BEARINGS 

IN  the  general  meaning  of  the  term,  a  bear- 
ing is  any  part  that  carries  weight  or  pres- 
sure and  at  the  same  time  rubs  over  an- 
other surface.  According  to  this  definition,  the 
portion  of  the  cylinder  walls  traversed  by  the 
pistons  are  bearings,  and  that  is  in  reality  the 
case,  but  the  term  has  come  to  be  applied  more 
specifically  to  the  part  of  the  machine  in  which 
another  part  revolves,  either  continuously  or 
intermittently.  Thus  the  portions  of  the  crank 
shaft  on  which  it  is  supported  and  the  parts 
of  metal  in  which  they  revolve  combine  to  form 
the  crank  shaft  bearings.  The  shaft  or  stud  on 
which  a  gear  or  wheel  is  mounted  and  on  which 
'*  revolves  is  the  bearing  of  that  gear  or  wheel. 
Although  they  are  concealed,  as  some  six- 
cylinder  motors  may  be  provided  with  as  many 
as  three  dozen,  or  more,  bearings — if  we  con- 
sider those  on  which  the  cam,  pump,  and 
magneto  shafts  and  the  gears  are  mounted — 

43 


44      THE  GASOLINE  MOTOR 

but  what  descriptions,  rules,  and  precautions 
apply  to  all  hold  true  in  the  largest  sense  when 
the  crank  shaft,  connecting  rod,  and  wrist  pin 
bearings  only  are  considered.  It  is  on  this 
latter  class  that  the  greatest  wear  of  the  mo- 
tor is  concentrated,  and  the  owner  who  under- 
stands and  inspects  these  need  fear  no  trouble 
from  the  cam  shaft  and  gear  bearings. 

The  expert  will  judge  of  the  condition  of  a 
motor  by  the  wear  that  has  occurred  in  the 
bearings  rather  than  by  any  exhibition  of  tem- 
porary power  that  it  may  develop  in  a  short 
test,  and  it  is  for  this  reason  that  the  "  gen- 
eral public "  runs  a  risk  whenever  it  buys  a 
second-hand  car  that  has  not  been  thoroughly 
overhauled  by  a  reputable  factory  or  inspected 
by  a  competent  engineer.  The  bearings  are  in 
reality  the  vitals  of  the  motor,  and  when  these 
are  worn  beyond  the  point  of  easy  adjustment 
or  renewal,  the  repairs  necessary  to  place  the 
machine  in  good  condition  would  oftentimes 
cost  more  than  the  entire  engine  is  worth.  But 
even  in  a  badly-worn  motor,  the  bearings  may 
be  "  taken  up  "  and  "  doctored  "  so  that,  for 
a  while  at  least,  the  engine  will  seem  to  run 
perfectly  and  develop  its  full  power.  This  will 
not  be  for  long,  however,  and  soon  the  motor 
will  begin  to  pound,  knock,  and  rattle  until  an 


BEARINGS  45 

examination  will  bring  to  light  the  true  condi- 
tion of  the  bearings. 

In  no  machine  are  the  bearings  subjected  to 
more  severe  usage  than  in  the  automobile  mo- 
tor. In  order  that  the  motor  car  power  plant 
shall  be  light  in  weight  and  occupy  but  a  small 
amount  of  space,  the  power  must  be  trans- 
mitted at  high  speeds.  In  many  an  automobile 
motor,  the  pressure  imparted  to  a  single  bear- 
ing during  a  certain  portion  of  its  revolution 
may  frequently  be  well  over  two  tons,  and  in 
this  same  bearing,  the  "  speed  of  rubbing  "  may 
approach  eight  or  nine  hundred  feet  per  min- 
ute. In  other  words,  at  normal  speeds  of  the 
motor,  about  a  sixth  of  a  mile  of  steel  surface 
will  rub  over  a  certain  point  in  each  crank  shaft 
bearing  during  every  minute  that  the  engine  is 
running. 

When  properly  lubricated,  an  iron  or  steel 
shaft  will  run  in  almost  any  kind  of  a  metal 
bearing  that  is  sufficiently  strong  to  carry  the 
weights  and  pressures  imposed  upon  the  shaft. 
The  friction  generated  between  two  different 
metals  that  rub  against  each  other,  however, 
varies  according  to  the  composition  of  those 
metals,  and  consequently  it  is  advisable  to  em- 
ploy some  material  for  a  bearing  that  will  offer 
a  minimum  resistance  to  the  turning  of  the 


46      THE  GASOLINE  MOTOR 

shaft.  Friction  must  be  reduced  between  all 
moving  surfaces  in  order  that  the  mechanical 
efficiency  of  the  machine  shall  be  high,  and  it  is 
in  the  bearings  that  a  large  amount  of  power 
may  be  absorbed. 

But  even  between  the  best-lubricated  sur- 
faces, employing  the  most  efficient  metal  as  a 
bearing,  some  wear  is  bound  to  occur.  The 
crank  shaft  of  a  four-  or  a  six-cylinder  motor 
is  forged  or  sawed  from  one  piece  of  steel, 
and  with  the  accurate  machining,  finishing,  and 
grinding  to  which  it  is  subjected,  it  becomes  an 
expensive  part  of  the  engine.  Consequently  it 
is  advisable  that  the  wear  of  bearings  of  such 
parts  shall  be  restricted  to  the  "  boxes  "  or  sur- 
rounding stationary  metal  in  which  the  shaft 
revolves  at  these  points.  In  order  that  all  wear 
shall  occur  here,  rather  than  in  the  shaft,  the 
boxes  are  made  of  or  lined  with  a  softer  metal. 
If  the  crank  shaft  is  of  hard  steel,  the  bearing 
metal  may  be  of  brass  or  bronze,  but  it  has 
been  found  that  babbitt  metals  give  the  most 
satisfactory  service  for  such  conditions — par- 
ticularly as  a  sufficiently  hard  crank  shaft  is 
difficult  to  produce  commercially. 

Not  only  is  a  babbitt  metal  softer  than  the 
steel  of  the  shaft  and  consequently  receives 
practically  all  the  wear  of  the  bearing,  but  it 


BEARINGS  47 

has  the  added  advantage  of  melting  at  com- 
paratively low  temperatures.  At  first  thought, 
this  may  seem  like  a  doubtful  advantage,  but 
in  case  of  a  failure  of  the  oil  supply  to  that 
bearing,  this  characteristic  may  be  the  means 
of  saving  the  crank  shaft,  and  possibly  the 
crank  case,  cylinders,  and  connecting  rods, 
from  rack  and  ruin. 

The  purpose  of  lubrication  is  to  reduce  fric- 
tion between  the  two  surfaces  in  contact.  Fric- 
tion generates  heat,  and  consequently  the  tem- 
perature of  a  bearing  to  which  a  sufficient  sup- 
ply of  oil  is  not  delivered  will  be  raised  to  a 
very  high  point.  This  high  temperature  will 
cause  both  parts  of  the  bearing  to  expand,  with 
the  result  that  the  fit  becomes  very  tight  and 
the  shaft  binds  or  "  seizes  "  in  its  box.  This  is 
the  familiar  u  hot  box,"  so  often  the  bane  of 
railroad  men,  and  if  the  shaft  is  still  run  under 
these  conditions,  the  bearing  material  will  be 
torn  out  and  the  surface  of  the  shaft,  axle,  or 
whatever  the  revolving  portion  happens  to  be, 
will  be  cut  and  abraded,  oftentimes  beyond  the 
possibility  of  repair.  It  is  such  accidents  as 
these  that  are  prevented  by  the  use  of  an  easily- 
melted  babbitt  metal. 

If  the  oil  supply  becomes  insufficient  so  that 
the  temperature  of  the  bearing  is  raised  above 


48      THE  GASOLINE  MOTOR 

a  certain  point,  the  babbitt  metal  will  be  melted 
and  will  run  out  of  its  container  before  any 
damage  can  be  done  to  the  shaft.  Efficient 
running  cannot,  of  course,  be  obtained  with  the 
bearing  "burned  out"  in  this  manner,  but  the 
babbitt  is  quickly  and  easily  renewed  and 
serves  as  a  sort  of  fusible  safety  valve  that 
saves  many  an  expensive  crank  shaft  replace- 
ment. 

Babbitt  metals  may  be  of  various  composi- 
tions and  proportions  and  many  contain  lead, 
but  those  which  have  been  found  to  give  the 
best  results  for  use  on  the  crank  shafts  of  auto- 
mobile motors  are  composed  only  of  tin,  anti- 
mony, and  copper.  If  lead  is  used  at  all  for 
this  purpose,  it  should  not  appear  in  propor- 
tions above  one  per  cent  of  the  total  compo- 
sition. Inasmuch  as  a  babbitt  metal  will  fuse 
at  a  comparatively  low  temperature  and  is 
much  softer  than  steel,  it  is  obvious  that  such 
a  material  will  not  withstand  heavy  pressures 
unless  reinforced  and  is  unsuited  for  structural 
purposes.  Consequently  the  babbitt  is  placed 
in  the  bearing  box  in  the  form  of  a  thin  lining 
within  which  the  shaft  revolves. 

When  the  shaft  is  "  lined  up  "  in  the  box,  the 
hot  babbitt  metal  may  be  poured  in  until  the 
space  is  entirely  filled.  When  the  babbitt  cools, 


BEARINGS  49 

the  shaft  may  be  turned,  and  when  lubricant 
has  been  introduced  in  the  oil  grooves  which 
should  have  been  provided  for  the  purpose,  the 
new  bearing  will  be  ready  for  use.  It  is  not  to 
be  expected  that  the  majority  of  motor  car 
owners  will  rebabbitt  the  crank  shaft  bearings 
themselves,  but  it  is  necessary  to  understand 
the  general  principles  of  such  bearing  design 
in  order  to  inspect  the  motor  intelligently  and 
to  determine  upon  the  repairs  needed. 

The  above  method  of  renewing  "  burned 
out "  bearings  applies  to  babbitts  in  general, 
but  the  severe  usage  that  automobile  engine 
crank  shaft  and  connecting  rod  bearings  are 
called  upon  to  withstand  necessitates  the  exer- 
cise of  a  certain  amount  of  additional  care. 
It  is  necessary  that  the  box  shall  fit  the  shaft 
perfectly,  so  that  there  can  be  no  "  play,"  and 
yet  the  shaft  must  be  allowed  to  turn  easily 
within  its  surrounding  babbitt  metal. 

As  was  stated  above,  the  shaft  may  be  easily 
loosened  from  the  babbitt  metal  after  the  latter 
has  cooled,  and  this  would  form  a  satisfactory 
type  of  bearing  were  it  not  advisable  that  some 
means  be  supplied  by  which  the  wear  could  be 
taken  up  without  renewing  the  entire  babbitt 
lining.  The  bearing  boxes  of  the  crank  shaft 
are  each  made  in  two  halves,  the  lower  portion 


50      THE  GASOLINE  MOTOR 

being  cast  integral  with  the  crank  case,  while 
the  upper  half  is  in  the  form  of  a  separate  cap 
that  may  be  held  in  place  by  two  or  four  bolts. 
In  this  case,  it  is  necessary  that  the  boxes  shall 
be  in  two  sections,  for  the  shape  of  the  crank 
shaft  prevents  it  from  being  slid  into  place 
lengthwise,  and  consequently  it  must  be  placed 
on  its  bearing  from  the  top.  In  some  designs 
of  motors  the  bearing  caps  form  the  lower 
half  of  the  box,  but  as  in  this  case  the  base  of 
the  motor  must  be  inverted  in  order  to  remove 
the  crank  shaft,  the  caps  will  still  be  consid- 
ered as  the  "  top  "  halves  of  the  boxes. 

There  may  be  dove-tail  grooves  cut  in  the 
inside  of  the  halves  of  the  boxes  to  retain  the 
babbitt  metal  after  it  has  been  poured  in  place. 
Consequently,  in  order  to  remove  the  cap  after 
renewing  the  babbitt  lining,  the  babbitt  metal 
must  be  cut  in  two  at  the  joint  between  the 
two  halves  of  the  box.  The  two  halves  of  the 
box,  instead  of  fitting  closely  together,  are  sep- 
arated by  thin  strips  of  copper  or  fiber  known 
as  "  shims  "  that  serve  to  relieve  the  shaft  from 
the  pressure  of  the  bolts  when  the  bearing  cap 
is  screwed  in  place.  In  other  words,  the  two 
halves  of  the  box  must  be  held  tightly  in  place 
by  means  of  the  bolts  and  nuts,  but  none  of 
this  pressure  should  rest  on  the  revolving  shaft, 


BEARINGS  51 

as  this  would  Bind  it  and  prevent  it  from  turn- 
ing easily.  Consequently  by  "  building  up  "  the 
space  between  the  two  halves  with  these  thin 
shims  the  proper  adjustment  may  be  obtained. 

These  shims  provide  the  method  of  taking 
up  the  wear  in  the  babbitt  that  will  eventually 
result.  By  loosening  the  box  retaining  bolts 
and  removing  the  required  number  of  shims, 
the  halves  of  the  box  will  be  brought  closer 
together.  When  the  bearing  cap  is  screwed 
securely  in  place,  the  shaft  should  be  able  to 
revolve  freely  without  binding,  and  yet  the  fit 
should  be  sufficiently  tight  to  prevent  any 
"  play "  at  right  angles  to  the  length  of  the 
shaft. 

The  pressure  of  a  shaft  should  not  be  con- 
centrated in  one  place,  but  should  be  distrib- 
uted over  as  large  a  surface  of  the  babbitt 
metal  as  is  possible.  A  few  years  ago,  when 
renewing  or  repairing  a  bearing,  it  was  con- 
sidered sufficient  to  pour  in  the  molten  metal 
or  to  remove  the  proper  number  of  shims — 
and  the  bearing  was  then  said  to  be  ready  for 
its  work.  But  even  though  no  play  was  appar- 
ent, it  was  possible  that  the  shaft  rested  on  only 
a  few  portions  of  the  bearing  surface;  and  the 
increased  attention  that  is  now  paid  to  the 
details  of  automobile  construction  is  no  better 


52      THE  GASOLINE  MOTOR 

exemplified  than  in  the  fact  that  nearly  all 
bearings  are  "  scraped  "  in.  This  operation  is 
simple  and  consists  merely  in  removing  any 
slight  excess  babbitt  metal  so  that  the  lining  fits 
the  shaft  throughout  its  entire  length  and  cir- 
cumference. The  babbitt  is  sufficiently  soft  to 
enable  it  to  be  peeled  or  scraped  with  a  sharp 
tool  provided  for  the  purpose,  and  no  great 
degree  of  skill  is  necessary  in  obtaining  the 
required  fit. 

In  order  to  determine  at  exactly  what  por- 
tions of  the  babbitt  lining  the  pressure  is  too 
great,  a  dye  or  paint  known  as  "blueing"  is 
used.  The  bearing  portion  of  the  crank  shaft 
is  painted  with  this,  and  the  cap  is  then  screwed 
in  place.  If  the  crank  shaft  is  then  turned  and 
the  cap  removed,  it  will  be  found  that  the 
blueing  has  been  transferred  from  the  bearing 
to  the  portions  of  the  babbitt  metal  on  which 
the  pressure  is  the  greatest.  These  portions 
should  then  be  shaved  with  the  tool  mentioned 
above,  and  the  same  test  repeated.  As  the 
excess  metal  is  removed,  it  will  be  found  that 
the  blueing  gradually  is  deposited  over  a  larger 
area  of  the  babbitt,  but  it  is  not  to  be  supposed 
that  the  fit  can  be  made  so  perfect  that  the 
color  will  be  distributed  evenly  over  the  entire 
surface.  Care  should  be  taken  to  screw  the 


BEARINGS  53 

bearing  cap  onto  the  shims  as  tightly  as  pos- 
sible each  time  the  blueing  test  is  to  be  made. 

There  is  nothing  that  will  heat  a  bearing  so 
quickly  as  a  poor  alignment  of  the  shaft  sup- 
ported by  it.  For  this  reason  gasoline  engine 
crank  shafts  are  made  exceptionally  strong  and 
heavy,  especially  those  that  are  supported  only 
at  their  extremities,  or  at  these  points  and  in 
the  center  of  their  length.  A  shaft  that  is 
bent  or  twisted  to  even  the  slightest  degree 
will  soon  "burn  out'*  all  of  its  bearings,  re- 
gardless of  the  amount  of  oil  that  may  be  fed 
to  them.  This  is  because  of  the  unequal  pres- 
sures on  the  different  sides  of  the  bearing  that 
allow  no  room  for  the  admission  of  the  film  of 
oil  or  other  lubricant  that  is  necessary  in  all 
cases  to  prevent  a  "  hot  box." 

On  the  other  hand,  the  bearings  must  all  be 
in  perfect  alignment,  for  to  set  one  slightly 
"  off  "  would  produce  the  same  result  as  though 
the  shaft  were  bent.  It  will  be  seen  that  the 
use  of  babbitt  produces  a  "  self-aligning  "  bear- 
ing, for  the  straight  shaft  may  be  set  in  its 
proper  position  and  the  molten  metal  poured 
around  the  interior  of  the  boxes. 

As  it  is  highly  important  that  the  cap  screws 
or  nuts  holding  the  bearing  cap  in  place  should 
remain  set  as  tightly  as  possible,  precautions 


54      THE  GASOLINE  MOTOR 

must  be  taken  to  prevent  any  of  these  from 
working  loose.  This  may  be  done  by  means 
of  a  cotter  pin  that  passes  through  a  hole  in 
each  bolt  and  through  a  pair  of  corresponding 
notches  cut  in  the  top  of  opposite  faces  of  the 
nut.  A  notch  is  generally  cut  in  the  top  of  each 
face  of  the  nut  in  order  that  the  latter  may  be 
held  securely  in  place  in  any  position.  A  con- 
tinuous wire  passing  through  all  of  the  bolts 
and  nuts  is  sometimes  used  instead  of  the  indi- 
vidual cotter  pins. 

Many  modern  automobile  motors  are  de- 
signed with  the  crank  shaft  running  in  ball 
bearings.  The  type  generally  used  consists  of 
a  row  of  balls  set  between  the  inner  and  outer 
edges  of  two  concentric  rings.  The  inside  of 
the  outer  and  the  outside  of  the  inner  ring 
are  grooved,  constituting  the  ball  "  race " 
which  forms  the  surface  upon  which  the  balls 
roll  and  which,  at  the  same  time,  serves  to  hold 
them  in  place.  Each  ball  of  the  same  bearing 
must  be  made  of  exactly  the  same  size  as  its 
companions — or  at  least  within  one  or  two  ten- 
thousandths  of  an  inch — and  each  one  must  be 
large  enough  and  of  sufficient  strength  to  with- 
stand, by  itself,  the  entire  pressure  in  that  bear- 
ing. The  inner  ring  slips  over  the  bearing 
portion  of  the  shaft  with  a  comparatively  tight 


HEARINGS  55 

fit,  while  the  outer  ring  remains  stationary  in 
its  bed  in  the  crank  case. 

The  inner  ring  turns  with  the  shaft,  thus 
causing  the  balls  to  roll  in  their  race.  Each 
ball  rolls  about  its  own  axis,  and  the  entire 
series  describes  a  circular  motion  in  the  same 
direction  as  that  taken  by  the  shaft,  but  con- 
siderably slower.  Consequently  there  is  no 
rubbing  in  such  a  bearing,  all  the  motion  being 
of  the  rolling  type,  and  as  this  reduces  friction 
to  a  minimum,  the  balls  may  be  run  without  oil, 
although  lubrication  of  the  proper  kind  would 
certainly  not  harm  the  bearing.  Ball  bearings 
are  adapted  only  for  a  two-bearing  crank  shaft, 
for  inasmuch  as  the  rings  must  be  slipped  over 
the  shaft,  it  would  be  manifestly  impossible  to 
provide  a  ball  bearing  in  the  center,  or  in  any 
other  portion  beyond  a  crank. 

Next  in  importance  to  the  main  bearings  of 
a  crank  shaft  are  those  by  which  the  connect- 
ing rods  communicate  their  motion  to  the 
cranks.  These  are  known  as  the  crank  pin 
bearings  or  the  "  big  end  "  of  the  connecting 
rod  bearings.  But  inasmuch  as  the  upper,  or 
smaller,  end  of  the  connecting  rods  are  termed 
the  wrist-pin  bearings,  the  other  end  may  be 
called  simply  the  connecting  rod  bearing. 

The  connecting  rod  bearings  are  similar  to 


56      THE  GASOLINE  MOTOR 

the  main  bearings  described  in  the  foregoing 
pages  and  are  renewed  and  adjusted  in  the 
same  manner.  It  is  probable,  however,  that 
these  receive  a  greater  amount  of  wear  than 
do  the  main  bearings,  inasmuch  as  the  former 
obtain  the  direct  impact  of  the  force  of  each 
explosion.  Furthermore,  the  box  of  the  con- 
necting rod  bearing  describes  a  complete  circle 
with  each  revolution  of  the  crank  shaft,  in 
addition  to  the  "internal  rotation"  of  the 
crank,  while  an  alternate  push  and  pull  is  de- 
livered to  it  by  the  connecting  rod  on  its  vari- 
ous strokes. 

Consequently  it  is  the  connecting  rod  bear- 
ings that  will  become  loose  and  require  "  taking 
up  "  before  any  attention  need  be  bestowed  on 
the  main  bearings.  The  wear  will  increase  in 
the  connecting  rod  bearing  as  the  play  becomes 
greater,  and  if  matters  are  not  remedied,  the 
box  may  eventually  be  broken,  with  the  result 
that  the  end  of  the  connecting  rod  thus  freed 
will  start  on  the  "  rampage  "  and  will  punch 
several  pieces  out  of  the  bottom  of  the  crank 
case. 

Brass  or  bronze  bearings  may  be  used  at 
the  big  end  of  the  connecting  rods,  but  the 
large  majority  of  motor  car  engines  are  pro- 
vided with  babbitted  bearings  at  these  points. 
It  is  especially  necessary  that  these  bearings 


BEARINGS  57 

should  be  scraped  to  a  perfect  fit  and  that  the 
shims  should  be  adjusted  properly  so  that  no 
side  play  will  be  apparent  when  the  connecting 
rod  is  moved  transversely  to  the  length  of  the 
crank  shaft.  When  renewing  the  babbitts  of 
connecting  rod  bearings  care  should  be  taken 
to  allow  the  connecting  rod  to  swing  free  be- 
fore the  molten  metal  is  poured  in.  If  this 
is  not  done,  the  connecting  rod  may  be  forced 
slightly  to  one  side  or  the  other  and  will  be 
held  permanently  in  this  position  when  the  bab- 
bitt cools.  This  will  induce  a  slight  side  thrust 
in  the  connecting  rod,  which  will  be  commu- 
nicated to  the  piston,  with  the  result  that  the 
side  of  the  latter  and  of  the  portion  of  the 
cylinder  wall  against  which  it  moves  will  be 
scored  and  worn  unduly. 

Inasmuch  as  the  connecting  rod  bearings  are 
subjected  to  such  a  variety  of  strains,  and  as 
looseness  at  these  points  will  result  in  serious 
wear,  it  is  doubly  necessary  that  the  nuts  and 
bolts  holding  the  bearing  caps  in  place  should 
be  securely  wired  or  held  tightly  by  means  of 
the  previously-mentioned  cotter  pins.  It  is  evi- 
dent that  the  base  of  the  large  end  of  the 
connecting  rod  forms  the  upper  half  of  the 
bearing  box,  while  the  cap  constitutes  the  lower 
end  and  is  attached  from  the  bottom. 

The  connecting  rod  bearings  on  some  motors 


58      THE  GASOLINE  MOTOR 

are  hinged  at  one  side  so  that  the  cap  may  be 
turned  away  from  the  crank  shaft  when  it  is 
desired  to  remove  the  connecting  rod.  In  this 
case  the  hinge  replaces  the  one  or  two  bolts 
or  nuts  on  one  side  of  the  box  and  is  held  in 
the  proper  position  by  those  on  the  other  side. 
While  it  may  be  easier  to  adjust  a  bearing 
provided  with  such  a  cap,  the  results  obtained 
can  hardly  be  expected  to  be  as  satisfactory  for 
high-grade  service,  as  is  the  case  when  the 
shims  may  be  used  on  both  sides  of  the  two 
halves  of  the  bearing. 

The  wrist-pin  bearing  is  located  at  the  upper, 
or  small,  end  of  each  connecting  rod,  and, 
although  it  also  carries  the  full  force  of  each 
explosion,  it  is  not  subjected  to  as  great  wear 
as  is  the  bearing  at  the  other  end  of  the  con- 
necting rod.  The  reason  for  this  is  that  this 
bearing  does  not  revolve  and  its  friction  sur- 
face is  reduced  to  the  comparatively  small  arc 
through  which  the  connecting  rod  swings. 
Wear  can  occur  here,  however,  and  because 
this  bearing  is  more  inaccessible  than  is  the 
crank  shaft  or  connecting  rod  bearing,  trouble 
at  the  wrist  pin  is  often  overlooked. 

The  wrist  pin  can  only  be  reached  by  the 
removal  of  the  piston  and  connecting  rod.  In 
the  majority  of  designs  the  wrist  pin  is  placed 


BEARINGS  59 

in  the  sides  of  the  piston  and  is  held  stationary 
by  small  keys  or  by  set  screws.  In  this  case, 
the  bearing  surface  is  formed  by  the  wrist  pin 
and  the  small  end  of  the  connecting  rod,  at 
which  point  the  greatest  wear  occurs.  This 
bearing  is  never  babbitted,  but  in  order  to 
reduce  the  wear  on  the  wrist  pin — which  is 
generally  made  of  hardened  steel — the  circular 
opening  in  the  upper  end  of  the  connecting  rod 
is  lined  with  a  bronze  or  brass  bushing  that 
forms  a  bearing  fit  over  the  wrist  pin.  It  is 
this  lining,  or  bushing,  that  will  wear  rather 
than  the  hardened  steel  wrist  pin,  but  as  the 
former  is  easily  removed  and  is  not  expensive 
to  replace,  the  renewal  of  this  bearing  is  a  com- 
paratively simple  matter. 

In  other  types  of  wrist  pin  bearings,  the  pin 
is  held  stationary  in  the  connecting  rod  opening 
and  turns  with  it  as  the  connecting  rod  swings 
through  its  arc  on  each  stroke  of  the  piston. 
With  such  a  design,  the  bearing  surface  is 
formed  by  each  end  of  the  wrist  pin  and  the 
openings  in  the  sides  of  the  piston  walls  in 
which  the  wrist  pin  rests.  In  order  to  form 
an  easily-replaced  bearing  surface,  these  open- 
ings in  the  piston  walls  are  lined  with  brass  or 
bronze  bushings  that  receive  the  major  part  of 
the  wear,  as  has  been  described  in  connection 


60      THE  GASOLINE  MOTOR 

with  the  bushings  fitted  to  the  opening  at  the 
small  end  of  the  connecting  rod. 

There  is  nothing  complicated  or  mysterious 
connected  with  the  renewal  or  repair  of  bear- 
ings, but  the  man  who  makes  such  replacements 
or  adjustments  must  be  an  accurate  and  careful 
worker,  and  while  he  need  not  be  a  "  born 
machinist,"  he  must  at  least  possess  the 
"  knack  "  of  handling  tools  properly.  And  he 
must,  above  all,  realize  that  the  designers  and 
manufacturers  of  his  motor  have  been  dealing 
in  measurements  of  the  thousandth  part  of  an 
inch  and  that  too  great  care  cannot  be  taken  in 
the  repair  of  bearings  to  obtain  a  perfect  fit. 

If  he  is  renewing  a  connecting  rod  or  a  wrist 
pin  bearing,  he  must  also  remember  that  the 
piston  has  formerly  been  traveling  over  a  cer- 
tain area  of  cylinder  surface  that  has  not  varied 
in  length  the  ten-thousandth  part  of  an  inch 
between  one  stroke  and  the  next.  Con- 
sequently, the  babbitts  or  bushings  should  be 
so  replaced  that  the  piston  shall  occupy  the 
same  position  relative  to  the  cylinder  walls  at 
the  top  and  bottom  of  its  stroke  that  it  did 
formerly.  In  other  words,  by  varying  the 
thickness  of  the  top  of  the  babbitt  he  is  replac- 
ing, he  may  change  the  "  center  "  of  the  bear- 
ing so  that  the  piston  will  start  on  its  upward 


BEARINGS  61 

stroke  from  a  different  point  than  was  previ- 
ously the  case.  Thus,  while  the  length  of 
travel  of  the  piston  will  be  the  same,  it  will 
traverse  a  slightly  different  portion  of  the 
cylinder  walls  under  the  new  conditions,  and 
this  will  have  the  effect  of  changing  the  com- 
pression and,  possibly,  of  wearing  the  piston 
and  rings  unduly. 


CHAPTER  IV 

THE  IGNITION  SYSTEM 

IT  was  the  application  of  the  electric  cur- 
rent to  the  ignition  system  Of  the  gasoline 
engine  that  first  enabled  these  new  forms 
of  power  plants  to  be  designed  with  sufficient 
compactness  and  to  possess  enough  flexibility 
to  render  their  use  practical  on  self-propelled 
vehicles.     Without  the  electric  ignition  system, 
the  speed  and  power  of  the  vehicle  could  not 
well  be  controlled,  and  the  explosions  would 
be  uncertain  and  irregular,  at  best. 

Those  of  us  who  are  familiar  with  the  elec- 
tric gas  lighters  that  were  in  popular  use  a  few 
years  ago  are  furnished  with  a  convincing 
demonstration  of  the  operation  of  the  first 
electric  ignition  systems.  By  pulling  a  chain,  a 
wire,  or  arm  was  rubbed  across  a  metal  point 
until  the  contact  thus  formed  was  suddenly 
broken.  This  arm  and  the  stationary  point 
formed  the  two  terminals  of  an  electric  circuit, 
which  caused  a  flash  of  blue  flame  when  the 

62 


THE  IGNITION.  SYSTEM      63 

contact  was  broken  as  the  one  was  "  wiped  " 
across  the  other.  The  flame  thus  formed  at 
the  instant  the  contact  was  broken  contained 
sufficient  heat  to  ignite  the  gas  escaping  from 
the  burner  to  which  the  device  was  attached. 

Sparks  will  be  formed  in  the  same  manner 
if  we  hold  two  wires,  connected  to  the  opposite 
poles  of  a  set  of  batteries,  in  both  hands  and 
wipe  the  bare  ends  across  each  other.  If  an 
arrangement  producing  this  effect  is  introduced 
into  the  gas  engine  cylinder  at  the  portion  in 
which  the  charge  is  compressed,  the  flash  re- 
sulting when  the  terminals  are  separated  will 
serve  to  ignite  the  explosive  mixture.  The 
movable  terminal  is  connected  to  a  rod  which 
passes  through  the  cylinder  walls  and  is  at- 
tached to  a  mechanism  actuated  by  a  cam  re- 
volved by  the  engine.  This  mechanism  is 
termed  the  "  make-and-break "  ignition  sys- 
tem for  the  reason  that  contact  of  these  ter- 
minals is  alternately  made  and  broken  to  pro- 
duce the  flash  of  electricity  that  explodes  the 
surrounding  charge. 

In  order  to  produce  a  flash  of  sufficient  size 
when  the  contact  is  broken,  the  nature  of  the 
current,  obtained  from  the  dry  cells  or  storage 
battery  is  changed  somewhat  by  conducting  it 
through  a  coil  of  wire  surrounding  a  bundle  of 


64      THE  GASOLINE  MOTOR 

bare  copper  wires.  This  is  known  as  a  spark 
coil,  and  while  it  is  generally  used  with  battery 
ignition  of  the  make-and-break  type,  magnetos 
may  be  designed  which  produce  the  proper 
kind  of  current  direct,  without  the  aid  of  the 
coil. 

An  ordinary  set  of  six  dry  cells,  connected  in 
series — or  like  with  unlike  poles — will  produce 
a  current  of  between  twenty  and  twenty-five 
amperes  at  a  pressure  of  about  nine  volts — as- 
suming each  battery,  when  new,  to  deliver 
twenty-five  amperes  at  a  pressure  of  one  and 
one-half  volts.  The  "  series  "  wiring  gives  the 
entire  set  the  combined  voltage  of  all  with  the 
average  amperage  of  one.  For  the  benefit  of 
those  who  have  forgotten  their  elementary 
physics,  let  it  be  remembered  that  the  ampere 
is  the  measure  of  current  amount,  or  flow,  while 
the  voltage  is  concerned  only  with  the  pressure 
of  the  current.  By  the  use  of  various  arrange- 
ments of  windings  of  wires,  the  voltage  may  be 
raised  with  a  corresponding  decrease  in  the 
amperage — and  vice  versa.  Thus,  if  a  coil  is 
used  that  doubles  the  original  number  of  am- 
peres produced  by  the  battery,  the  voltage  will 
be  halved. 

The  make-and-break  type  of  ignition  has 
been  used  successfully  for  many  years,  but  with 


THE  IGNITION  SYSTEM      65 

the  perfection  of  the  magneto,  it  has  been 
largely  supplanted,  in  automobile  practice,  at 
least,  by  the  "  jump  spark,"  or  "  high-tension" 
system.  Because  of  the  fact  that  the  latter  sys- 
tem is  less  expensive  to  construct  and  is  highly 
efficient,  it  will  be  found  also  on  the  majority 
of  the  older  cars  not  equipped  with  a  magneto. 

It  was  found,  after  the  general  adoption  of 
the  make-and-break  ignition  system,  that  a 
flame  was  not  necessary  for  the  combustion  of 
a  properly-mixed  charge  in  the  engine  cylinder. 
In  fact,  a  tiny  spark,  scarcely  one-sixteenth  of 
an  inch  long  and  no  larger  around  than  a  pin, 
was  discovered  to  be  sufficient  to  produce  the 
ignition  of  the  charge.  Although,  of  small 
volume,  such  a  spark  generates  intense  heat, 
and  it  is  upon  this  quality,  rather  than  upon 
area,  that  the  charge  depends  for  its  ignition — 
although  it  is  claimed  that  a  large  flame  will 
produce  more  complete,  rapid,  and  con- 
sequently more  efficient,  combustion.  But  the 
jump  spark  possesses  the  advantage  of  requir- 
ing no  moving  parts  projecting  through  the 
cylinder  walls  into  the  combustion  chamber, 
and  its  greater  simplicity  over  that  of  the  make- 
and-break  system  has  resulted  in  its  almost  uni- 
versal adoption  by  automobile  manufacturers. 

It  has  been  stated  in  a  preceding  paragraph 


66      THE  GASOLINE  MOTOR 

that  the  voltage  produced  by  the  average  bat- 
tery set  will  not  exceed  nine  or  ten,  and  even- 
the  pressure  generated  by  the  ordinary  magneto 
is  not  greater  than  this.  But  air  is  not  a  good 
conductor  of  electricity  and  forms  a  very  high 
resistance  to  the  passage  of  a  current.  It  is 
only  when  the  high  resistance  of  an  air  gap  is 
encountered  in  its  circuit,  however,  that  a  spark 
will  be  formed  by  the  current,  and  consequently 
the  form  of  electricity  used  in  this  system  must 
have  resistance-overcoming  properties.  But  it 
is  only  by  raising  the  voltage  of  the  current 
that  even  a  short  air  gap  can  be  bridged  by  the 
spark.  In  fact,  a  pressure  of  somewhat  over 
fifty  thousand  volts  is  required  to  produce  a 
spark  less  than  an  inch  long  in  the  air. 

Although  only  called  upon  to  jump  a  gap 
about  a  sixteenth  of  an  inch  across,  the  ordin- 
ary high-tension  current  is  capable  of  bridging 
a  space  eight  or  ten  times  this  width  in  order 
that  ample  pressure  will  always  be  assured  for 
the  formation  of  the  spark.  Furthermore,  the 
warm  gases  in  which  the  spark  is  formed  in  the 
cylinder  increase  the  resistance  ordinarily  en- 
countered and  it  is  consequently  necessary  to 
raise  the  voltage  above  the  amount  that  would 
be  needed  were  the  plug  exposed  to  the  open 
air. 


THE  IGNITION  SYSTEM      67 

These  conditions  make  advisable  a  pressure 
of  from  twelve  thousand  to  thirty  thousand 
volts  in  the  ordinary  jump  spark  system,  and 
it  is  from  this  voltage  that  the  term  "  high 
tension "  is  obtained.  The  nine  or  ten  volts 
delivered  by  the  batteries  are  transformed  to 
this  larger  amount  by  means  of  an  induction 
coil — or  what  is  more  generally  termed  merely 
the  "coil."  This  is  in  reality  a  "step-up" 
transformer,  since  it  transforms  the  current 
from  one  of  low  voltage  to  another  of  two  or 
three  thousand  times  its  original  pressure. 

This  transformer  consists  of  two  coils  of 
wire,  one  surrounding  the  other.  The  inner 
coil  is  composed  of  a  comparatively  few  num- 
ber of  turns  of  rather  coarse  wire  wound 
around  a  soft  iron  core,  and  is  termed  the 
"  primary "  winding,  since  the  current  from 
the  batteries  is  led  directly  through  it.  The 
outer  coil  is  composed  of  many  turns  of  a  very 
fine  wire,  all  of  which  are  thoroughly  insulated 
from  each  other  and  from  the  inner  winding. 
This  outer  coil  is  termed  the  "  secondary " 
winding  and  is  the  one  from  which  the  high- 
tension,  or  transformed,  current  is  taken. 

This  secondary  current  is  "  induced "  from 
the  primary  winding  through  which  the  battery 
current  passes  and  possesses  a  voltage  that  has 


68      THE  GASOLINE  MOTOR 

increased  over  its  original  amount  in  the  same 
proportion  that  the  number  of  turns  in  the  sec- 
ondary winding  bears  to  those  in  the  primary. 
Therefore,  if  the  original  battery  voltage  is 
ten  and  there  are  a  thousand  times  as  many 
turns  in  the  secondary  winding  as  in  the  prim- 
ary, the  resulting  high-tension  current  will  have 
a  pressure  of  ten  thousand  volts. 

The  principle  of  the  coil  is  dependent  en- 
tirely upon  that  peculiar  electric  property 
known  as  u  induction."  Around  every  wire 
through  which  an  electric  current  passes  are 
invisible  "  lines  of  force  "  similar  to  those  that 
emanate  from  an  electro-magnet.  These  lines 
of  force  surround  the  wire  throughout  its 
length,  and  arrange  themselves  in  a  spiral  for- 
mation. Insulation  has  no  effect  on  these  lines 
of  force,  and  they  may  be  collected  from  wires 
which  are  separated  from  each  other  by  sev- 
eral thicknesses  of  current-confining  material. 
It  is,  of  course,  necessary  to  use  insulated  wires 
in  the  construction  of  these  coils,  for  otherwise 
the  current  would  merely  pass  to  adjoining 
turns  and  would  not  travel  the  entire  length  of 
the  winding — and  therefore  as  great  a  number 
of  lines  could  not  be  collected. 

If  an  additional  layer  or  layers  of  wire  is 
wound  around  the  first  series  of  turns,  the  lines 


THE  IGNITION  SYSTEM      69 

of  force  will  be  collected,  or  "  induced,"  by  this 
second  coil,  and  will  constitute  the  secondary 
current.  The  induction  effect  is  greatly  in- 
creased if  the  primary  current  is  allowed  to  ac- 
cumulate, or  "pile  up,"  and  discharge,  alter- 
nately, for  this  surging  of  the  current  creates 
a  sort  of  "  overflow  "  from  the  original  con- 
taining wires. 

Ohm's  Law,  which  states  that  the  number  of 
amperes  in  an  electric  circuit  is  equal  to  the 
voltage  divided  by  the  number  of  ohms  of 
resistance  encountered,  shows  that  the  current 
will  be  changed  by  its  passage  through  the 
primary  winding.  The  induced  current  is  fur- 
ther changed,  and  when  collected  by  the  sec- 
ondary winding  and  sent  through  its  long  coils, 
we  have  the  high-tension  circuit  mentioned  in 
the  preceding  paragraph. 

If  the  reader  remembers  that  it  is  but  one 
hundred  and  ten  volts  that  is  used  to  operate 
our  electric  lights  and  that  five  hundred  will 
run  a  trolley  car,  he  may  wonder  why  it  is  not 
dangerous  to  handle  as  great  a  pressure  as  the 
thirty  thousand  volts  that  are  used  in  connec- 
tion with  the  ignition  system  of  a  motor  car. 
But  it  is  the  combination  of  great  voltage  with 
high  amperage  that  is  dangerous,  and  if  it  Is 
remembered  that,  as  the  former  is  increased, 


70      THE  GASOLINE  MOTOR 

the  latter  is  reduced  correspondingly,  it  will 
be  realized  that  the  ordinary  high-tension  ig- 
nition current  possesses  a  quantity,  or  flow,  of 
scarcely  one  one-hundredth  of  an  ampere. 

If  we  liken  the  electric  current  to  a  flow  of 
water  in  a  pipe,  we  have  the  amperes  corres- 
ponding to  the  quantity  of  the  flow,  or  the  num- 
ber of  gallons  that  will  be  delivered  at  the  out- 
let in  a  given  time.  Continuing  this  analogy, 
the  voltage  of  the  electric  current  will  be  the 
pressure,  or  "  head  "  in  the  water  system,  and 
the  current  from  the  batteries  before  the  coil 
is  reached  will  correspond  to  a  moderate  flow 
of  water  at  a  comparatively  low  pressure.  Af- 
ter the  coil  has  transformed  the  current  to  the 
high  voltage,  we  have  the  conditions  of  a  very 
small  opening  in  the  water  pipe  containing  a 
tremendous  pressure.  Such  a  stream  will  pos- 
sess but  small  flow,  but  its  high  pressure  will 
enable  it  to  be  "  squirted  "  to  a  far  greater  dis- 
tance than  would  be  the  case  were  its  volume 
larger  and  its  "  head"  less.  Although  the 
pressure  is  high,  its  quantity  is  so  low  that  the 
stream  can  do  but  little  damage  and  would 
scarcely  more  than  tickle  the  flesh  of  a  person 
against  whom  it  is  directed. 

Thus  it  is  with  the  ignition  current.    It  can 
"  tickle,"  rather  viciously,  sometimes,  as  many 


THE  IGNITION  SYSTEM      71 

persons  will  aver,  but  the  amount  of  electricity 
involved  is  so  slight  as  to  render  the  high  pres- 
sure harmless.  Nevertheless,  it  is  well  to  avoid 
allowing  the  fingers  or  the  arm  to  become  a 
part  of  the  high-tension  circuit,  for  the  result 
may  be  startling  as  well  as  annoying. 

But  in  order  that  the  high  voltage  shall  be 
induced  in  the  secondary  coil,  the  primary  cir- 
cuit must  be  alternately  made  and  broken 
between  one  stroke  and  the  next.  Consequently 
proper  "  piling  up,"  or  "  surging,"  of  the  cur- 
rent will  be  effected.  This  is  accomplished  by 
means  of  an  "  interrupter  "  that  either  vibrates 
rapidly  or  "  snaps  "  once  at  the  formation  of 
each  spark.  The  former  is  the  more  common 
type  used  with  battery  ignition  and  is  known 
as  a  vibrating  coil.  A  circuit  breaker  is  gen- 
erally incorporated  in  the  mechanism  of  a 
magneto,  and  consequently  when  such  an  in- 
strument is  used,  the  vibrator  on  the  coil  is 
dispensed  with.  It  is  the  vibrator  on  each  coil 
that  forms  the  "  buzz "  that  can  be  heard 
whenever  the  box  cover  is  removed,  and  that 
often  furnishes  a  simple  test  for  determining 
the  condition  of  the  ignition  system  of  the  par- 
ticular cylinder  with  which  that  coil  is  con- 
nected. 

The  vibrator  is  a  flat,  spring  steel  piece  that 


72      THE  GASOLINE  MOTOR 

rests  near  one  end  of  the  soft  iron  core  around 
which  the  primary  coil  is  wound.  The  springy 
nature  of  the  vibrator  ordinarily  holds  it 
against  a  small,  adjustable  contact  point  that 
should  be  set  about  an  eighth  of  an  inch  from 
the  end  of  the  above-mentioned  soft  iron  core. 
The  primary  coil  is  so  wired  that  its  current 
passes  through  the  vibrator  steel  and  the  con- 
tact point  against  which  it  rests.  As  soon  as 
the  current  travels  through  the  coil  surround- 
ing the  soft  iron  core,  however,  the  latter  be- 
comes magnetized  and  draws  the  steel  vibrator 
toward  it.  This  breaks  the  circuit,  the  mag- 
netism of  the  iron  core  disappears,  and  the 
vibrator  returns  to  its  original  position  against 
its  contact  point.  But  this  action  again  forms 
the  circuit,  and  the  same  operation  is  repeated 
as  long  as  the  current  is  allowed  to  flow  to- 
ward the  coil. 

This  is  the  same  principle  on  which  an  elec- 
tric bell  is  rung,  but  the  vibrator  of  the  coil 
makes  and  breaks  the  circuit  much  more 
rapidly  on  account  of  the  less  weight  of  the 
moving  parts.  This  vibration  of  the  coil  in- 
terrupter is  so  rapid — hundreds  a  second  prob- 
ably— that  the  resulting  spark  is  practically 
continuous  and  shows  no  effect  of  the  breaks 
In  the  circuit. 


THE  IGNITION  SYSTEM      73 

Even  though  it  is  the  primary  current,  of 
low  voltage,  that  is  interrupted  by  the  vibrator, 
the  frequency  of  these  interruptions  causes  a 
slight  sparking,  or  arcing,  at  the  contact  points. 
These  are  therefore  subjected  to  rather  a  high 
degree  of  heat,  as  well  as  a  large  amount  of 
wear,  and  it  is  necessary  that  they  be  made  of 
a  material  that  will  resist  both.  Platinum  has 
been  found  to  be  unusually  suitable  for  this 
purpose,  but  owing  to  its  high  cost,  only  a 
small  amount  in  the  form  of  two  points,  or 
"  buttons,"  is  used.  One  of  these  points  is 
placed  in  the  vibrator  steel,  and  the  other  is 
embedded  in  the  end  of  the  screw  against  which 
the  first  rests.  Thus  the  actual  contact  is  made 
against  these  heat-and-wear-resisting  platinum 
points,  and  it  is  evident  that  upon  their  proper 
action  depends  the  formation  of  the  spark  in 
the  cylinder  with  which  that  particular  vibra- 
tor is  connected. 

Notwithstanding  the  fact  that  platinum  pos- 
sesses high  heat-resisting  properties,  the  con- 
stant arcing  at  the  contact  points  will  even- 
tually form  a  sort  of  corrosion  in  which  min- 
ute particles  of  the  material  are  carried  from 
one  point  to  the  other  in  the  direction  in  which 
the  current  flows.  If  the  current  is  reversed, 
the  corrosion  will  take  place  in  the  other  di- 


74      THE  GASOLINE  MOTOR 

rection,  and  consequently  the  platinum  point 
that  formerly  lost  a  part  of  its  material  will 
gradually  be  "  built  up  "  again.  This  corro- 
sive action  is  known  as  "  pitting,"  and  while  it 
may  be  reduced  to  a  certain  extent  by  reversing 
the  terminals  of  the  battery,  as  described,  the 
platinum  will  occasionally  require  additional 
attention. 

A  coil  having  badly  pitted  contact  points  on 
the  vibrator  will  "  stick "  and  will  cease  to 
form  a  spark  regularly.  It  is  often  difficult  to 
distinguish  between  trouble  arising  from  badly- 
pitted  contact  points  and  that  caused  by  weak 
or  nearly-exhausted  batteries,  as  either  ailment 
produces  the  same  symptoms  of  irregular  run- 
ning and  "  jerking  "  in  the  motor.  For  this 
reason,  a  volt  and  ampere  meter  for  measuring 
the  pressure  and  amount  of  the  current  de- 
livered by  the  batteries  should  form  a  part  of 
every  automobile  owner's  tool  equipment. 

It  is  the  amperage,  rather  than  the  voltage, 
that  is  reduced  through  continued  use  of  the 
batteries,  and  when  this  quantity  falls  below 
nine  or  ten,  the  cells  should  be  discarded — or 
recharged,  in  the  case  of  a  storage  battery. 
But  if  the  ignition  occurs  irregularly  when  the 
batteries  are  delivering  the  proper  amount  of 
current,  it  is  probable  that  the  trouble  lies  in 


THE  IGNITION,  SYSTEM      75 

the  pitted  condition  of  the  platinum  contact 
points  of  the  vibrator  of  the  coil.  Fine  emery 
cloth  rubbed  over  the  surfaces  of  contact 
should  serve  to  remedy  matters.  It  should  be 
made  certain  that  the  resulting  surfaces  on  the 
platinum  points  are  not  only  rubbed  smooth, 
but  level,  as  well,  in  order  that  the  entire  area 
of  each  will  rest  in  contact  and  the  current  will 
not  be  concentrated  at  a  small  portion. 

It  is  probable  that  there  will  be  a  screw  ad- 
justment on  the  vibrator  by  means  of  which 
the  force  with  which  the  latter  rests  against 
its  contact  point  may  be  regulated.  If  the  vi- 
brator is  set  too  tight,  an  undue  amount 
of  current  will  be  required  to  magnetize  the 
core  of  the  coil  sufficiently  to  pull  the  vibrator 
away  from  its  contact  point,  and  the  batteries 
will  soon  "  run  out."  On  the  other  hand,  the 
tension  of  the  vibrator  should  be  sufficient  to 
enable  it  to  spring  away  from  the  core  of  the 
coil  as  soon  as  the  circuit  is  broken,  for  other- 
wise the  vibrator  will  lag  and  will  not  be  as 
"  lively  "  as  is  necessary  to  obtain  the  best  re- 
sults. 

The  contact  screw  should  be  set  so  that  the 
vibrator  rests  about  three-thirty-seconds  of  an 
inch  from  the  end  of  the  magnetic  core.  After 
the  tension  of  the  vibrator  has  been  set  to  ap- 


76      THE  GASOLINE  MOTOR 

proximately  the  proper  amount,  the  ear  must 
be  trusted  for  the  correct  adjustment  of  the 
contact  screw.  When  the  switch  is  thrown  on 
and  the  motor  turned  until  current  flows 
through  the  coil,  the  resulting  buzz  emanating 
from  the  vibrator  should  be  decided  and  force- 
ful. If  this  buzz  is  exceedingly  high-pitched, 
it  is  an  indication  that  the  vibrator  has  been  set 
too  tight,  and  its  tension  should  be  loosened 
if  unscrewing  the  contact  point  slightly  does 
not  lower  the  tone.  It  must  be  remembered 
that  the  tension  of  the  vibrator  can  be  changed 
by  turning  the  contact  screw.  If  this  screw  is 
turned  down  so  that  it  forces  the  vibrator  to- 
ward the  iron  core,  the  tension  will  be  greater 
than  will  be  the  case  if  the  contact  point  is 
turned  to  the  left. 

If  the  buzz  of  the  vibrator  is  pitched  lower 
than  was  formerly  the  case,  it  is  an  indication 
that  the  contact  point  should  be  screwed  down, 
or  that  the  tension  of  the  vibrator  should  be 
tightened.  It  is  probable  that  turning  the  con- 
tact screw  to  the  right  will  produce  the  proper 
result.  While  these  changes  in  the  position  of 
the  contact  screw  are  being  made,  the  switch 
should  be  left  turned  on  so  that  the  variations 
in  the  pitch  of  the  vibrator  buzz  may  be  de- 
tected. When  an  evenly-pitched,  vigorous 


THE  IGNITION,  SYSTEM     77 

buzz  has  been  secured,  the  switch  should  be 
thrown  on  and  off  several  times  to  make  cer- 
tain that  the  response  of  the  vibrator  is  in- 
stant and  positive.  The  switch  should  then 
be  left  on  and  the  vibrator  allowed  to  buzz 
for  several  seconds  in  order  that  it  may  be  de- 
termined whether  the  pitch  of  the  sound  will 
change,  or  not  If  there  is  a  change  noticeable, 
the  contact  screw  should  be  readjusted  until 
the  pitch  of  the  buzz  remains  constant  as  long 
as  the  circuit  is  closed. 

The  coil  and  batteries  or  magneto  by  no 
means  form  the  entire  ignition  system,  al- 
though the  generation  of  the  spark  depends  en- 
tirely upon  them.  The  spark  must  be  regu- 
lated to  occur  at  the  proper  point  in  the  stroke 
of  the  piston,  as  a  continuous  spark  would  not 
only  waste  the  current,  but  would  cause  the 
ignition  of  the  charge  during  the  upward 
stroke  and  would  result  in  an  impulse  in  the 
reverse  direction  that  would  prevent  the  mo- 
tor from  running  for  more  than  half  a  turn. 

The  device  by  which  the  time  of  the  occur- 
rence of  the  spark  is  regulated  is  called  the 
timer.  This  consists,  in  its  essentials,  of  a 
hard  rubber  disc  provided  with  a  copper  or 
brass  segment.  A  metal  pin,  roller,  or  ball 
rests  against  the  outer  edge  of  the  disc,  and 


78      THE  GASOLINE  MOTOR 

as  the  latter  is  revolved,  the  electrical  circuit 
is  completed  whenever  the  two  metal  portions 
come  in  contact  with  each  other.  The  hard 
rubber  being  a  non-conductor  of  electricity, 
prevents  the  flow  of  the  current  at  all  other 
times.  The  disc  of  the  timer,  known  as  the 
"  commutator,"  is  so  geared  that  it  revolves 
in  unison  with  the  motor. 

Inasmuch  as  the  explosion  occurs  in  each 
cylinder  only  at  every  second  stroke  of  a  four- 
cycle motor,  the  commutator  on  this  type  of 
engine  is  geared  to  revolve  at  one-half  the 
speed  of  the  crank  shaft.  In  the  two-cycle  mo- 
tor, on  the  other  hand,  the  explosion  occurs  in 
each  cylinder  at  every  revolution,  and  conse- 
quently the  commutator  should  turn  at  crank 
shaft  speed. 

Although  the  spark  is  intended  to  occur  ap- 
proximately at  the  extreme  upper  end  of  the 
compression  stroke,  a  few  degrees  variation 
both  above  and  below  this  point  is  necessary 
in  order  to  obtain  the  desired  speed  and  power 
flexibility  of  the  gasoline  motor.  At  high 
speeds,  the  spark  should  be  timed  to  occur  be- 
fore the  piston  reaches  the  extreme  top  of  its 
Stroke,  while  at  slower  revolutions  of  the  mo- 
tor the  ignition  should  take  place,  in  some  in- 
stances, just  after  the  piston  has  started 


THE  IGNITION.  SYSTEM      79 

to  descend.  This  variation  in  timing  is  ob- 
tained by  swinging  the  contact  piece  of  the 
timer — known  as  the  brush — either  forward 
or  backward  through  an  arc  corresponding  to 
the  range  of  advance  and  retard. 

If  this  brush  is  swung  in  a  direction  opposite 
to  that  of  the  revolution  of  the  commutator, 
the  metal  portions  will  meet  sooner,  with  the 
result  that  the  spark  will  occur  earlier,  or  will 
be  "  advanced."  If,  however,  the  brush  is 
swung  to  a  point  farther  along  in  the  direction 
of  rotation  of  the  commutator,  the  spark  will 
occur  later,  or  will  be  u  retarded."  These 
variations  of  position  of  the  brush  are  gen- 
erally obtained  by  means  of  a  lever  attached  to 
the  steering  post  or  wheel. 

It  is  evident  that  the  current  must  pass  from 
the  brush  to  the  metal  segment  of  the  commu- 
tator in  order  to  complete  the  circuit  through 
the  timer  and  thus  form  the  spark.  It  is  the 
primary  current,  or  low-tension  current  from 
the  battery  or  magneto,  that  passes  through 
the  timer,  and  as  this  is  of  low  voltage  and  is 
therefore  easily  discouraged,  it  is  necessary 
that  the  contact  points  be  kept  clean  in  order 
that  its  travel  may  be  made  easy.  Timers  are 
generally  protected  from  dirt,  but  the  particles 
that  will  naturally  be  worn  off  from  the  metal 


80      THE  GASOLINE  MOTOR 

and  rubber  commutator  and  brush  should  be 
cleaned  out  before  its  accumulation  becomes 
deposited  on  the  contact  points  and  interferes 
with  perfect  electrical  connection. 

A  few  years  ago,  the  majority  of  battery  ig- 
nition systems  employed  a  separate  coil  for 
each  cylinder  of  the  motor.  Each  coil  in  this 
system  is  connected  with  an  individual  brush 
that  operates  against  the  same  commutator  as 
do  the  brushes  for  the  other  cylinders.  With 
such  a  system,  the  primary  circuit  leads  from 
one  terminal  of  the  battery  to  the  primary 
winding  of  the  coil,  through  this  and  the  vi- 
brator to  the  brush  of  the  timer  reserved  for 
that  particular  coil  and  cylinder,  and  thence 
through  the  switch  to  the  other  terminal  of  the 
battery.  This  order  may  be  reversed,  or  the 
timer,  switch,  and  coil  may  be  placed  in  any 
consecutive  position,  provided  the  current 
passes  through  all  in  its  travel  from  one  ter- 
minal of  the  battery  to  the  other.  The  sec- 
ondary, or  high-tension  current  is  led  from  the 
terminal  of  the  secondary  winding  on  the  coil 
to  the  spark  plug  of  the  proper  cylinder. 
There  should  be  a  "  ground  "  wire  to  serve  for 
the  return  of  the  secondary  current.  This  may 
lead  from  any  part  of  the  primary  circuit  to  a 
clean  metal  connection  on  the  motor. 


THE  IGNITION  SYSTEM     81 

The  multiple  coil  system  is  still  used  to  a 
large  extent,  but  an  elaboration  of  it  will  be 
found  on  many  of  the  modern  cars.  This  con- 
sists of  the  use  of  but  a  single  coil  for  all  of 
the  cylinders  of  the  motor.  This  is  done  by 
means  of  a  distributor,  which  is  a  sort  of 
"  glorified  timer  "  consisting  of  a  commutator 
provided  with  as  many  segments  as  there  are 
cylinders  in  the  motor.  This  distributor  re- 
ceives the  current  from  a  single  coil  and  de- 
livers it  to  the  proper  cylinder  as  the  various 
connections  are  made.  The  timer  still  per- 
forms its  function  of  completing  the  circuit 
from  the  source  of  current  only  at  the  proper 
instant,  and  leaves  the  distributor  to  serve  the 
purpose  of  a  "  switch "  to  "  sidetrack "  the 
current  and  deliver  it  at  the  various  cylinders 
in  turn. 

If  it  should  ever  become  necessary  to  re- 
move any  part  of  the  timer,  or  to  change  the 
length  of  the  spark  control  rods,  the  greatest 
care  should  be  taken  to  make  certain  that  the 
motor  is  properly  timed  when  the  various  por- 
tions are  replaced.  This  can  best  be  done  by 
setting  the  spark  lever  in  its  central  position, 
removing  a  plug  from  one  of  the  cylinders,  and 
introducing  a  rod  or  long  screw  driver  into  the 
opening  for  the  purpose  of  determining  the  ex- 


82      THE  GASOLINE  MOTOR 

act  top  of  the  stroke  of  the  piston.  When  the 
flywheel  is  turned,  the  top  of  the  stroke  should 
be  marked  on  the  rod  or  screw  driver  as  the 
latter  is  forced  upward  by  the  piston. 

If  the  spark  plug  is  laid  with  its  large  nut 
resting  on  the  cylinder  head,  and  the  switch 
is  thrown,  the  time  of  the  occurrence  of  the 
spark  can  be  readily  observed  as  the  motor  is 
turned  slowly  by  hand.  This  spark  should  oc- 
cur in  this  particular  plug  just  as  the  piston  of 
that  cylinder  reaches  the  top  of  its  stroke,  as 
indicated  by  the  change  in  the  direction  of  the 
movement  of  the  rod  or  screw  driver.  If  the 
spark  occurs  too  soon  or  too  late,  the  commu- 
tator should  be  moved  backward  or  forward  to 
remedy  the  respective  trouble.  Although  if  the 
timer  is  set  properly  for  one  cylinder  it  is 
probable  that  the  spark  in  the  others  is  also 
timed  correctly,  it  is  well  to  test  each  to  make 
certain  that  there  has  been  no  uneven  wear  in 
the  contact  segments  of  the  commutator  or  the 
brush. 


CHAPTER  V 
MAGNETOS 

THE  perfection  of  the  magneto  and  its 
application  to  cars  of  all  classes  and 
sizes  has  marked  the  most  important 
step  in  gasoline  motor  ignition  since  the  intro- 
duction of  the  electric  spark.  The  magneto  is 
now  considered  one  of  the  most  vital  parts  of 
the  car,  and  while  it  is  possible  for  the  motor 
to  be  run  for  many  miles  on  the  batteries  that 
form  the  auxiliary  ignition  sources,  the 
mechanical  current  generator  has  left  the  field 
of  the  desirable  accessories  and  has  become  an 
actual,  physical  portion  of  the  engine. 

The  operation  of  the  magneto  is  simple,  its 
whys  and  wherefores  are  logical,  and  if  one  in- 
vestigates the  subject,  even  superficially,  he  will 
discover  that  the  much-maligned  machine  sel- 
dom gives  trouble,  and  that  when  it  does,  such 
action,  or  failure  to  act,  is  due  to  neglect, 
abuse,  or  some  other  perfectly  legitimate  rea- 
son, rather  than  "  pure  cussedness "  on  the 
part  of  the  instrument  itself.  If  the  mere  me- 

83 


84      THE  GASOLINE  MOTOR 

chanical  aspect  is  considered;  if  it  is  realized 
that  the  magneto  consists  mainly  of  a  bundle 
of  wires  which,  when  revolved  near  the  ends 
of  a  magnet,  collects  that  magnetism  and  sends 
it  through  the  circuit  in  the  form  of  the  electric 
current,  and  that  consequently  the  magneto  is 
a  converter  that  changes  part  of  the  mechanical 
energy  of  the  motor  into  the  spark-forming 
fluid,  the  chief  idea  of  magneto  principles  may 
be  more  easily  grasped. 

To  be  sure,  the  magneto  is  delicate,  and  for 
that  reason  it  should  never  be  dissected  by  the 
amateur,  but  inasmuch  as  what  few  adjust- 
ments it  has  are  readily  accessible,  it  is  seldom 
that  the  machine  need  to  be  taken  apart.  The 
platinum  points  of  the  contact  breaker,  usually 
located  in  the  small  box  on  the  end  of  the 
armature  shaft,  may  need  to  be  smoothed  with 
emery  paper  occasionally  if  they  have  become 
pitted  from  excessive  sparking,  but  this  is  a 
simple  operation  and  is  not  greatly  different 
from  the  care  given  to  the  vibrator  of  the 
dashboard  spark  coil,  as  described  in  the  pre- 
ceding chapter. 

A  few  drops  of  oil  should  be  fed  to  the 
lubricating  cups  or  holes  of  the  armature  shaft 
as  often  as  the  directions  call  for — usually 
about  once  every  five  hundred  miles — but  aside 


MAGNETOS  85 

from  this,  the  owner  can  generally  forget  that 
he  has  a  magneto,  and  will  only  be  reminded 
of  the  fact  by  the  pleasing  absence  of  ignition 
trouble.  If  ignition  trouble  does  occur,  it  is 
more  than  probable  that  the  fault  lies  with  the 
plugs,  timer,  or  wires,  rather  than  with  the 
magneto. 

The  man  who  drives  a  magneto-equipped 
car  knows  that  the  current  producer  is  run  by 
a  gear  Connected,  either  directly  or  through 
the  medium  of  other  gears  with  the  crank  shaft 
of  the  motor.  He  knows,  then,  that  the  mag- 
neto is  driven  positively  and  that  there  is  a 
constant  relation  between  its  speed  and  the 
number  of  revolutions  of  the  motor. 

But  does  he  know  that  it  is  absolutely  nec- 
essary that  a  certain  position  of  the  armature 
shall  always  correspond  with  a  similar  position 
of  the  crank  shaft  of  the  motor,  and  that  con- 
sequently the  same  teeth  of  the  driving  gears 
must  always  mesh?  He  will  most  assuredly 
be  made  aware  of  this  if  he  disconnects  his 
magneto  and  then  fails  to  replace  the  gears  so 
that  exactly  the  same  teeth  are  in  mesh,  for 
even  the  difference  of  a  single  tooth  between 
the  normal  positions  of  the  armature  and  crank 
shaft  will  prevent  the  magneto  from  delivering 
a  sufficient  spark  to  enable  the  motor  to  run. 


86      THE  GASOLINE  MOTOR 

The  reason  for  this  is  simple.  All  of  these 
direct-driven  magnetos  are  of  the  alternating 
current  type,  as  this  form  allows  of  the 
simplest  construction  of  armature  and  wind- 
ings. The  alternating  current  generator  ob- 
tains its  name  from  the  fact  that  there  are  no 
regularly-defined  north  and  south  poles  at  any 
part  of  the  circuit,  as  these  keep  changing  con- 
tinuously, or  alternating. 

During  each  revolution  of  the  armature  of 
the  alternating  current  magneto,  there  are  but 
two  positions  at  which  a  current  will  be  formed. 
Now  the  spark  in  any  cylinder  of  a  motor  is 
required  at  about  the  top  of  the  compression 
stroke  of  the  piston  in  that  cylinder.  Conse- 
quently when  the  piston  is  at  the  top  of  its 
compression  stroke,  ready  for  the  spark  that 
will  ignite  the  charge,  the  armature  of  the  mag- 
neto must  be  in  one  of  its  two  current-generat- 
ing positions,  and  there  must  therefore  be  a 
constant  relation  between  the  position  of  the 
crank  shaft,  to  which  each  piston  is  connected, 
and  that  of  the  revolving  part  of  the  mag- 
neto. 

If,  now,  the  driving  gear  of  the  magneto  is 
returned  to  its  place  without  regard  to  the 
teeth  of  the  next  gear  with  which  it  meshes, 
it  will  be  seen  that  the  proper  relation  between 


MAGNETOS  87 

the  position  of  the  armature  and  that  of  the 
crank  shaft  will  not  be  maintained.  Under 
these  conditions,  when  the  piston  is  at  the  top 
of  the  compression  stroke,  ready  for  the  spark, 
the  armature  will  not  be  in  a  position  at  which 
a  current  can  be  generated,  and  there  can  con- 
sequently be  no  spark  formed  at  the  plug. 
Conversely,  when  the  armature  has  been  re- 
volved to  the  position  at  which  a  current  will 
be  formed,  none  of  the  pistons  will  be  requir- 
ing the  spark,  and  this  consequent  lack  of 
"team  work"  will  prevent  the  operation  of 
the  motor. 

In  order  to  maintain  this  team  work  be- 
tween the  armature  of  the  magneto  and  the 
crank  shaft  of  the  motor,  the  intermeshing 
teeth  of  the  gears  should  be  marked  with  a 
prick  punch  before  they  are  removed,  so  that 
they  may  be  returned  to  their  proper  place 
without  trouble.  Only  in  this  manner  can  ac- 
curate results  be  obtained,  if  it  is  at  any  time 
necessary  to  remove  all  or  part  of  the  magneto 
driving  gear. 

The  magnets  forming  the  "  fields  "  of  the 
magneto  in  which  the  armature  revolves  are  of 
the  permanent  kind;  that  is,  they  do  not  depend 
upon  windings  and  a  separate  electric  current 
for  their  excitation,  as  is  the  case  with  some 


88      THE  GASOLINE  MOTOR 

of  the  larger  generators.  These  magnets  may 
be  considered  to  be  the  most  faithful  part  of 
the  machine,  for  they  generally  retain  their 
strength  under  all  conditions  of  rest  or  work, 
and  it  is  upon  them  that  the  proper  operation 
of  the  magneto  largely  depends. 

A  magneto  in  which  the  magnets  have  be- 
come weakened  is  useless  for  ignition  purposes 
until  the  fields  can  be  remagnetized,  and  as  this 
can  only  be  done  at  the  factory,  the  machine  in 
its  entirety  must  be  removed  from  the  motor. 
It  is  a  comparatively  easy  matter  to  determine 
whether  or  not  the  fields  have  lost  their  mag- 
netism by  placing  a  piece  of  iron  or  steel  with- 
in close  range  of  the  base  or  sides  of  the  mag- 
neto. An  appreciable  pull  will  be  exerted  by 
the  magnets  if  they  still  retain  their  strength, 
although  it  is  not  to  be  supposed  that  the  force 
thus  exhibited  will  be  very  vigorous  from  such 
a  small  machine. 

If  the  magneto  has  been  disconnected  from 
its  driving  gear  for  any  reason,  the  amount  of 
magnetism  remaining  in  the  fields  will  be  best 
determined  by  turning  the  armature  shaft  with 
the  hand.  A  resistance  should  be  offered  to 
the  turning  at  first  until  a  certain  point  is 
reached,  after  which  the  armature  should  ex- 
hibit a  strong  tendency  to  fly  forward  to  a  new 


MAGNETOS  89 

position,  one  hundred  and  eighty  degrees  be- 
yond its  former  normal  position  of  rest.  This 
activity  of  the  armature  is  one  of  the  best 
guides  to  the  amount  of  magnetism  remaining 
in  the  fields. 

Many  magnetos  that  have  been  installed  on 
old  motor  cars  not  previously  so  equipped  are 
of  the  friction-driven,  direct-current  type  that 
produces  a  uniform  spark  at  any  point  through- 
out the  armature  revolution.  Current  from 
these  may  be  used  to  charge  a  storage  battery 
for  the  operation  of  electric  lights  or  to  supply 
auxiliary  ignition  current  for  starting.  The 
positively-driven,  alternating-current  magneto 
may  also  be  used  to  operate  electric  lights  on 
the  car,  but  this  type  of  current  cannot  be 
stored  in  a  battery,  and  consequently  the  lights 
are  available  only  when  the  motor  is  running. 
The  magneto,  however,  is  not  primarily  an 
electric-lighting  outfit,  and  unless  it  is  especially 
designed  for  the  double  purpose,  a  separate 
machine  should  generally  be  used  for  supplying 
illuminating  current. 


CHAPTER  VI 
CARBURETORS  AND  THEIR  FUEL 

ALTHOUGH  gasoline  is  inflammable  in 
its  liquid  state,  its  combustion  is  not  suf- 
ficiently rapid  to  approach  the  explosive 
point  necessary  to  render  its  energy  available 
in  the  automobile  engine  cylinder.  The  proper 
proportion  of  gasoline  vapor  and  air,  however, 
forms  a  mixture  that  is  highly  inflammable  and 
that  will  be  entirely  consumed  in  the  engine 
cylinder  under  ordinary  conditions  within 
about  one-twentieth  of  a  second  after  the 
formation  of  the  spark.  This  rapid  combus- 
tion so  neady  approaches  the  instantaneous 
action  of  an  explosion  that  it  may  be  con- 
sidered as  such  in  all  ordinary  discussions  of 
the  gasoline  engine.  Literally,  however,  the 
gasoline  engine  is  not  an  explosion  motor,  but 
rather  is  it  an  engine  of  the  internal  combustion 
type.  To  obtain  this  gasoline  vapor  in  an 
easily-controlled  form  the  carburetor  was  de- 
signed as  one  of  the  most  important  adjuncts  of 

the  automobile. 

90 


CARBURETORS  91 

The  first  form  of  carburetors,  or  "  vapor- 
izers," as  they  were  called  then,  employed  a 
flat,  woven  lamp  wick  over  which  the  gasoline 
flowed.  This  spread  the  fuel  out  over  a  com- 
paratively large  surface  and  rendered  evapora- 
tion rapid  and  simple.  The  chamber  contain- 
ing this  wick  was  placed  in  the  line  of  the  in- 
take pipe  of  the  motor  and  was  connected  with 
the  cylinders  on  the  descent  of  the  pistons  on 
the  suction  stroke  through  the  medium  of  the 
various  inlet  valves.  In  a  four-cycle  motor,  the 
piston  acts  as  a  suction  pump  on  alternate 
downstrokes  and  serves  to  draw  the  charge 
into  the  cylinder.  This  suction  created  the 
necessary  current  of  air  to  facilitate  evapora- 
tion of  the  gasoline  on  the  wick,  and  by  regu- 
lating the  size  of  the  passages,  the  proper  pro- 
portion of  air  and  gasoline  vapor  could  be  ob- 
tained. 

The  modern,  high-speed  automobile  motor, 
with  its  varying  demands  upon  the  carburetor, 
created  the  necessity  for  a  more  delicate,  flexi- 
ble, and  compact  vaporizer  than  was  to  be 
found  in  the  u  lamp  wick  "  type.  Consequently 
the  wick  was  replaced  by  a  small,  slender,  hol- 
low tube  having  a  cone-shaped  opening  at  its 
upper  end  through  which  the  gasoline  from  the 
feed  pipe  was  made  to  pass.  Fitting  into  the 


92      THE  GASOLINE  MOTOR 

upper  end  of  this  tube,  and  pointed  to  the  same 
angle,  was  a  cone-shaped  "  needle  "  that  could 
be  moved  in  and  out  of  the  opening.  If  this 
needle  was  unscrewed  slightly  so  that  it  did  not 
form  a  tight  fit  with  the  end  of  the  tube,  a 
small  ring  would  be  formed  through  which  the 
gasoline  must  pass  when  sucked  by  the  alter- 
nate down  strokes  of  the  pistons.  This  tube 
and  needle  constitute,  under  various  guises,  the 
"  needle  valve  "  with  which  practically  every 
modern  carburetor  is  equipped. 

When  the  gasoline,  rushing  through  the 
small  tube,  strikes  the  restricted  opening  of  the 
needle  valve,  it  is  broken  up  into  a  fine  spray 
which,  under  proper  conditions,  will  become 
vaporized  almost  as  soon  as  it  comes  in  con- 
tact with  a  current  of  air.  This  air  current 
is  induced  by  the  same  pump-like  effect  of  the 
pistons  as  that  which  sucks  the  gasoline 
through  the  needle  valve,  and  thus  it  occurs 
only  when  the  charge  is  desired  in  the  cylinders. 

But  the  carburetor  is  not  merely  to  provide 
a  compact  device  for  vaporizing  the  gasoline, 
for  it  must  also  furnish  a  means  of  regulating 
the  proportion  of  gas  to  air.  Gasoline  vapor 
is  only  highly  inflammable  when  mixed  with 
the  proper  quantity  of  air,  and  if  this  propor- 
tion is  varied  above  one  limit  or  below  an- 


CARBURETORS  93 

other,  ignition  of  the  charge  will  not  occur  in 
the  cylinders.  In  fact,  the  allowable  variation 
in  the  proportion  of  gasoline  vapor  to  air  is 
restricted  between  very  narrow  limits,  and 
should  not  change  more  than  four  or  five  per 
cent,  from  one  extreme  to  the  other.  The 
proportion  of  gasoline  vapor  to  air  by  weight 
is  about  one  to  eleven,  although  this  will  vary 
somewhat  with  the  different  grades  of  fuels. 

The  point  to  be  emphasized,  however,  is  the 
fact  that  the  proper  proportion  of  air  to  gaso- 
line vapor,  however  it  may  vary  with  different 
grades,  should  be  kept  constant  at  all  speeds 
of  the  motor  whenever  that  particular  grade 
of  fuel  is  used.  By  volume,  about  97J4  per 
cent,  of  the  mixture  should  be  air  and  the 
remainder  gasoline  vapor,  and  it  is  the  device 
that  will  the  most  nearly  maintain  this  propor- 
tion under  all  conditions  of  speed,  temperature, 
and  air  pressure  that  will  prove  to  be  the  most 
delicate  and  flexible  carburetor. 

A  carburetor  may  be  adjusted  for  different 
motors,  or  for  different  operating  conditions  of 
the  same  motor,  by  means  of  the  needle  valve. 
The  farther  end  of  the  slim  rod  on  which  the 
needle  point  is  mounted  terminates  in  a  thread 
and  finger  nut  that  projects  through  the  shell 
of  the  carburetor.  By  turning  this  nut  in  one 


94      THE  GASOLINE  MOTOR 

direction,  the  needle  valve  is  screwed  up  to- 
ward the  cone-shaped  end  of  the  tube  and  the 
orifice  through  which  the  gasoline  may  pass  is 
thus  reduced  in  size.  This  will  decrease  the 
amount  of  gasoline  sprayed  into  the  air  pas- 
sage and  will  consequently  change  the  composi- 
tion of  the  mixture.  This,  however,  should 
not  be  confused  with  throttling  the  motor. 
When  the  needle  valve  is  tightened,  the 
volume  of  the  mixture  passing  to  the  cylinders 
is  the  same,  for  it  is  only  the  proportion  of 
gasoline  vapor  in  that  mixture  that  is  changed. 

Throttling  consists  in  restricting  the  size  of 
the  opening  through  which  the  mixture  passes, 
and  thus  limits  the  amount  of  the  charge  that 
reaches  the  cylinders  at  each  suction  stroke  of 
the  piston.  Throttling  is  used  to  reduce  the 
power — and  consequently  the  speed — de- 
veloped by  the  motor,  while  a  decrease  in  the 
amount  of  gasoline  supplied  to  the  air  through 
the  needle  valve  may  serve  to  increase  the 
power  through  an  improvement  in  the  nature 
of  the  mixture. 

Since  the  gasoline  vapor,  by  volume,  forms 
only  about  three  per  cent,  of  the  explosive 
mixture  admitted  to  the  cylinders,  a  slight 
variation  in  the  size  of  the  needle  valve  open- 
ing will  result  in  a  marked  change  in  the  com- 


CARBURETORS  95 

position  of  the  charge  and  may  make  all  jthe 
difference  between  poor  and  perfect  running  of 
the  motor.  Consequently  the  needle  valve  nut 
should  be  moved  but  the  small  fraction  of  a 
turn  for  each  adjustment.  A  motor  which  may 
refuse  absolutely  to  run  at  one  position  of  the 
needle  valve  may  give  perfect  results  if  the 
nut  is  unscrewed  but  the  eighth  of  a  turn. 

In  view  of  the  marked  difference  in  the  re- 
sults obtained  from  the  use  of  mixtures  that 
are  ujust  right,"  and  those  which  vary  but  a 
slight  percentage  in  the  proportion  of  gasoline 
vapor  to  air,  it  may  be  well  to  examine,  super- 
ficially, the  effects  of  "  rich "  and  "  weak " 
charges,  and  therefrom  to  obtain  a  list  of 
"  symptoms  "  which  may  aid  us  to  diagnose 
motor  trouble  properly. 

We  all  know  that  air — or  oxygen — is  re- 
quired to  support  combustion.  "Snuffing"  a 
candle  is  merely  covering  its  end  so  that  air 
cannot  reach  the  flame.  For  the  same  reason, 
gasoline  in  a  covered  tank  cannot  burn,  no  mat- 
ter how  great  the  heat  applied  to  it.  The  heat 
of  the  electric  spark  in  the  cylinder,  although 
intense,  does  not  cover  a  sufficiently  large  area 
to  ignite  any  charge  except  that  composed  of 
the  proper  proportion  of  gasoline  vapor  and 
air.  If  there  is  too  much  gasoline  vapor,  mak- 


96      THE  GASOLINE  MOTOR 

ing  a  "rich"  mixture,  there  will  not  be  suffi- 
cient air  in  the  charge  to  support  the  entire 
combustion  of  the  gas,  and  the  burning  will  be 
slow — if  it  takes  place  at  all.  The  same  con- 
ditions will  prevail  if  there  is  an  insufficient 
supply  of  air  for  a  given  quantity  of  gasoline 
vapor,  and  consequently  a  rich  mixture  may  be 
obtained  by  reducing  the  air  flow  as  well  as  by 
adding  to  the  amount  of  gas  admitted  to  the 
mixing  chamber. 

A  rich  mixture  will  cause  irregular  ex- 
plosions in  the  cylinders,  and  will  often  emit  a 
black,  pungent  smoke  at  the  exhaust.  The 
motor  will  probably  overheat  easily,  due  to  the 
slow-burning  properties  of  the  mixture  and  the 
resulting  fact  that  a  large  portion  of  the  cylin- 
der walls  uncovered  by  the  pistons  will  be  ex- 
posed to  the  flame.  In  some  instances,  the? 
cylinders  will  miss  fire  at  regular  intervals, 
thus  changing  the  synchronism  of  the  impulses 
with  a  well-defined  and  periodic  "  skip  "  in  the 
sound  of  the  explosions. 

While  these  are  by  no  means  certain  symp- 
toms of  a  rich  mixture,  the  first  test  to  be  made 
should  be  to  tighten  the  needle  valve  adjust- 
ment slightly  whert  the  motor  is  running  and  to 
note  any  resulting  improvement  in  the  regu- 
larity of  the  explosions.  It  may  sometimes  be 


CARBURETORS  W 

difficult  to  distinguish  between  the  symptoms  of 
a  rich  and  a  weak  mixture,  but  the  readjustment 
of  the  needle  valve  as  just  described  will  at 
least  serve  to  locate  the  trouble  or  to  eliminate 
one  or  the  other  possibility  from  considera- 
tion. 

When  a  mixture  is  "  starved ",  or  when 
there  is  an  insufficient  supply  of  gasoline  vapor 
to  unite  with  the  air  admitted  to  the  cylinders, 
the  charge  will  not  be  highly  inflammable  and 
may  not  be  ignited  by  the  small  spark  formed 
at  the  plug.  Even  when  ignition  does  take 
place,  the  resulting  power  impulse  will  be  weak 
because  of  the  comparatively  small  amount  of 
pressure-producing  gas  in  the  mixture.  The 
explosions  may  occur  regularly  for  a  while,  but 
there  will  be  a  marked  decrease  in  the  power 
developed  by  the  motor,  and  owing  to  the  fact 
that  weak  mixtures  may  be  slow-burning, 
"  back-firing  "  will  often  result  in  some  engines 
to  which  such  a  charge  has  been  fed. 

On  the  other  hand,  if  a  motor  will  run  at  all 
on  a  weak  mixture,  it  will  produce  better  re- 
sults than  would  be  the  case  were  the  charge 
too  rich  in  gasoline  vapor.  Consequently  the 
needle  valve  should  be  closed  as  much  as  is 
consistent  with  smooth  running  of  the  motor, 
but  the  moment  a  loss  of  power  or  irregular  ex- 


98      THE  GASOLINE  MOTOR 

plosions  occur,  the  mixture  should  be  enriched. 

At  low  speeds  of  the  motor,  the  pumping  ac- 
tion of  the  pistons  is  not  as  great  as  is  the  case 
at  high  revolutions,  and  consequently  the  suc- 
tion drawing  the  gasoline  through  the  needle 
valve  is  diminished.  For  this  reason,  the  needle 
valve  opening  must  be  made  larger  or  the  air 
passage  restricted  for  slow  speeds  of  the 
motor,  and  it  was  consequently  necessary,  on 
the  old,  non-automatic  vaporizers,  to  increase 
the  gasoline  supply  whenever  the  revolutions 
of  the  motor  were  to  be  reduced.  The  modern 
carburetor  is  sufficiently  automatic  in  its  action 
to  provide  the  proper  mixture  within  wide 
ranges  of  speed  change  of  the  motor,  but  even 
nowadays  it  is  often  found  necessary  to  in- 
crease the  gasoline  supply  or  to  reduce  the 
amount  of  air  admitted  to  the  intake  pipe 
whenever  it  is  desired  to  throttle  the  motor 
down  to  a  very  low  number  of  revolutions  per 
minute. 

The  automatic  action  of  the  ordinary  car- 
buretor is  obtained  by  increasing  the  air  sup- 
ply at  higher  speeds  of  the  motor.  Conse- 
quently the  motorist  will  realize  that  when- 
ever the  needle  valve  is  to  be  set,  such  regula- 
tion should  be  made  when  the  motor  is  well 
throttled,  for  if  an  ample  gasoline  supply  is 


CARBURETORS  99 

obtained  at  low  speeds,  the  mixture  will  cer- 
tainly be  sufficiently  rich  at  increased  revolu- 
tions. If,  on  the  other  hand,  the  .carburetor 
should  be  set  to  supply  a  proper  mixture  at 
high  speeds,  the  mixture  would  be  impover- 
ished when  the  motor  is  throttled,  and  irreg- 
ular running  would  result. 

The  air  for  the  operation  of  the  motor  at 
ordinary  speeds  is  supplied  through  a  fixed 
opening  in  the  carburetor  connected  with  the 
chamber  into  which  the  gasoline  spray  is  intro- 
duced. In  addition  to  this,  most  carburetors 
are  supplied  with  an  "  auxiliary  air  opening  " 
which  serves  to  furnish  the  additional  air  nec- 
essary for  the  mixture  at  high  speeds  of  the 
motor.  The  fixed  opening,  being  restricted  in 
size,  cannot  admit  the  increased  quantity  of  air 
demanded  by  the  higher  speeds  of  the  motor. 
The  auxiliary  opening  is  provided  with  some 
form  of  automatic  valve  which  may  consist 
either  of  a  series  of  ball  "  checks,"  a  spring- 
actuated  "mushroom  valve,"  or  a  series  of 
special  valves,  each  of  which  opens  at  succes- 
sively increased  speeds  of  the  motor. 

All  of  these  devices  operate  on  the  same 
principle,  however,  and  allow  the  increased  suc- 
tion of  the  motor  to  add  to  the  size  of  the  air 
passage  automatically — either  by  the  farther 


100    THE  GASOLINE  MOTOR 

opening  of  a  single  valve,  or  by  the  successive 
opening  of  different  valves.  Some  carburetors 
are  provided  with  an  adjustment  by  means  of 
which  the  "  delicacy,"  or  ease  of  opening,  of 
the  auxiliary  air  valve  may  be  regulated.  This 
may  be  done  by  means  of  a  nut  and  screw 
which  will  increase  or  decrease  the  tension  of 
the  controlling  spring.  If  this  spring  is  set 
with  a  high  tension,  the  auxiliary  valve  will 
act  only  when  the  motor  is  exerting  great  suc- 
tion, or  at  fast  speeds. 

The  regulation  of  the  auxiliary  valve  is  an 
adjustment  that  should  be  made  only  after  the 
needle  valve  has  been  set  properly  for  slow 
speeds  of  the  motor.  When  this  condition  is 
obtained,  the  throttle  should  be  opened  and 
the  further  adjustment  of  the  carburetor  for 
high  speeds  of  the  motor  should  then  be  made 
through  the  auxiliary  air  valve.  In  other 
words,  the  needle  valve  should  be  set  so  that 
the  motor  runs  properly  at  low  speeds,  while 
the  adjustment  of  the  auxiliary  air  valve  should 
be  made  only  to  secure  smooth  operation  at 
a  high  number  of  revolutions. 

It  is  not  to  be  understood  that  less  gasoline 
is  actually  required  at  high  speeds  of  the  motor 
because  the  supply  often  needs  to  be  cut  down 
at  the  needle  valve  under  these  conditions. 


CARBURETOR^  f\  j  ,  J  ;  1 


The  actual  amount  required  at  high  speeds  is, 
of  course,  greater  than  is  the  case  at  slow,  on 
account  of  the  greater  number  of  explosions 
in  the  former  instance.  But  the  suction  of  the 
motor  generally  increases  the  gasoline  flow  be- 
yond the  demands  of  the  cylinders  at  high 
speeds,  and  it  is  for  this  reason  that  the  auto- 
matic auxiliary  air  supply  is  provided  to  fur- 
nish the  additional  air  required  to  support  com- 
bustion. In  fact,  at  heavy  loads,  when  the  total 
amount  of  gasoline  consumed  must  be  great, 
a  secondary  jet  of  fuel  is  brought  into  action 
in  some  carburetors.  This  is  known  as  the 
"multiple-jet  "  type  and  is  found  on  some  of 
the  large  engines  that  must  possess  a  speed 
and  power  variation  between  wide  ranges.  The 
action  of  these  various  jets  is  entirely  auto- 
matic and  is  dependent  upon  the  speed  and  fuel 
requirements  of  the  motor. 

Were  the  gasoline  fed  directly  from  the  fuel 
tank  to  the  needle  valve  of  the  carburetor  it  is 
evident  that  the  rate  of  flow  of  the  liquid  would 
depend,  to  a  large  extent,  upon  the  amount  in 
the  tank  and  upon  the  position  of  the  car.  This 
would  cause  each  charge  to  differ  in  the  pro- 
portion of  gasoline  vapor  to  air,  and  it  is 
hardly  probable  that  the  motor  could  be  run 
at  all  under  such  conditions.  In  order  that  the 


102    THtt  GASOLINE  MOTOR 

pistons  may  suck  the  gasoline  from  a  level  that 
does  not  vary  with  the  amount  of  fuel  in  the 
tank  or  the  position  of  the  car,  a  separate  com- 
partment is  provided  in  the  carburetor.  This 
is  known  as  the  u  float  chamber,"  and  it  is 
from  this  compartment  that  the  gasoline  passes 
through  the  needle  valve  into  the  vaporizing 
or  mixing  chamber. 

A  cork  or  hollow  metal  float  is  placed  in  this 
float  chamber  and  is  mounted  on  a  lever  con- 
nected with  a  valve  located  at  the  end  of  the 
gasoline  feed  pipe.  As  the  gasoline  is  ad- 
mitted to  the  chamber,  the  float  rises  and  closes 
the  valve  controlling  the  flow  of  fuel.  As  the 
gasoline  is  sucked  through  the  needle  valve 
from  the  float  chamber,  the  float  in  the  latter 
lowers,  and  the  fuel  is  again  admitted  by  the 
opening  of  the  above-described  valve.  The 
float  and  valve  are  exceedingly  delicate  in  their 
operation  and  the  gasoline  is  thus  kept  at  a 
constant  level  in  the  chamber  under  all  condi- 
tions of  the  car  and  tank. 

The  stem  upon  which  the  float  of  some  car- 
buretors is  mounted  is  sometimes  threaded  and 
provided  with  a  nut  by  means  of  which  the 
float  may  be  raised  or  lowered.  This  furnishes 
an  adjustment  for  varying  the  level  in  the  float 
chamber  and  determining  at  what  point  the 


CARBURETORS  103 

flow  of  gasoline  shall  be  cut  off  by  the  auto- 
matic valve.  The  float  is  supposedly  properly 
regulated  when  the  carburetor  leaves  the  fac- 
tory, but  the  stem  may  become  bent  or  the  car- 
buretor may  be  applied  to  a  motor  other  than 
that  for  which  it  was  originally  designed.  In 
either  of  these  events,  it  may  be  found  neces- 
sary to  raise  or  lower  the  float  before  the 
proper  level  of  gasoline  can  be  maintained  in 
the  chamber. 

If  the  float  is  too  high  on  its  stem,  the  gaso- 
line control  valve  may  not  be  operated  until 
the  fuel  overflows  in  its  chamber.  This  is 
known  as  a  "  flooded "  carburetor  and  pro- 
duces a  rich  mixture  which  will  ultimately  pre- 
vent the  proper  operation  of  the  motor.  Turn- 
ing down  the  gasoline  supply  at  the  needle 
valve  will  not  remedy  this,  for  the  fuel  will 
reach  the  vaporizing  chamber  by  another 
route.  A  flooded  carburetor  often  gives 
trouble,  and  while  it  may  be  remedied  easily, 
the  amateur  may  experience  difficulty  in  locat- 
ing its  source. 

As  soon  as  it  is  discovered  that  a  carburetor 
has  become  flooded,  the  needle  valve  should 
be   tightened    so    that   no    gasoline    can   pass 
through    it,    and   the   motor   should   then  be 
cranked.     This   will   serve   to   evaporate   the 


104    THE  GASOLINE  MOTOR 

excess  gasoline  in  the  float  chamber  and  reduce 
the  level  to  the  point  at  which  it  will  not  over- 
flow. The  exact  number  of  turns  and  fractions 
of  turns  through  which  the  needle  valve  nut 
was  moved  should  have  been  noted  in  order 
that  the  valve  may  be  reset  to  its  original 
position  after  the  surplus  fuel  has  been 
"  cranked  out." 

A  float  that  is  set  too  low  on  its  stem  will 
close  the  fuel  supply  valve  before  a  sufficient 
amount  of  the  fuel  has  flowed  into  the  cham- 
ber, and  will  form  a  "  lean  "  mixture  at  high 
speeds  of  the  motor — even  though  the  needle 
valve  should  be  opened  wide.  The  obvious 
remedy  for  such  a  condition  is  to  raise  the 
float  until  the  gasoline  will  be  maintained  at 
the  proper  level.  If  there  is  no  nut  and  screw 
adjustment  by  which  the  float  may  be  raised, 
the  arm  to  which  it  is  attached,  and  which  is 
connected  with  the  valve,  may  be  bent  slightly. 

But  the  motorist  should  not  "  jump  at  con- 
clusions "  and  assume  that  the  float  is  improp- 
erly set  the  moment  the  carburetor  begins  to 
flood  or  the  motor  appears  to  "  starve  "  at  high 
speed.  The  first  condition  may  be  caused  by 
a  piece  of  dirt  or  other  foreign  matter  that 
may  have  become  lodged  on  the  valve  seat 
and  prevented  the  valve  from  closing  when  the 


CARBURETORS  105 

gasoline  reached  the  proper  level  in  the  float 
chamber.  This  will  produce  exactly  the  same 
results  as  will  a  high  float  and  is  a  trouble 
that  will  more  often  occur  in  the  average 
carburetor. 

The  difficulty  may  generally  be  remedied 
easily  by  draining  the  gasoline  from  the 
float  chamber  after  the  valve  in  the  main 
supply  pipe  has  been  turned  off.  The  offend- 
ing foreign  matter  will  generally  be  carried 
with  the  gasoline  as  the  latter  is  drained, 
and  the  valve  in  the  feed  pipe  may  again  be 
opened  as  soon  as  the  drain  cock  is  shut  off. 
If  this  fails  to  remedy  matters,  it  is  probable! 
that  the  difficulty  lies  with  the  float. 

A  clogged  gasoline  pipe  or  dirty  strainer 
will  produce  the  same  effect  on  the  operation  of 
the  motor  as  will  a  float  that  is  set  too  low  on 
its  stem.  When  the  motor  seems  to  starve  at 
high  speed,  and  it  is  evident  that  there  is  suf- 
ficient gasoline  in  the  tank,  the  union  should  be 
disconnected  at  the  point  where  the  feed  pipe 
joins  the  carburetor.  If  there  appears  to  be 
an  ample  flow  through  this  pipe  when  the  main 
valve  is  opened,  it  is  probable  that  the  stop- 
page has  occurred  in  the  strainer.  If  the  flow 
through  the  main  feed  pipe  is  not  free,  how- 
ever, it  is  possible  that  the  vent  hole  in  the  filler 


106    THE   GASOLINE   MOTOR 

cap  on  the  tank  has  become  stopped  or  that  the 
latter  has  been  screwed  down  too  tightly.  In 
the  gravity  feed  systems,  some  method  must  be 
provided  to  allow  the  air  to  flow  into  the  tank 
to  replace  the  gasoline  fed  to  the  carburetor. 
If  there  is  no  hole  in  the  filler  cap,  the  latter 
should  not  be  screwed  down  so  tightly  that  an 
airtight  joint  will  be  formed. 

Probably  the  simplest  method  of  determin- 
ing whether  the  trouble  lies  in  a  low  float  is 
to  prime  the  carburetor  and  to  observe  the 
ease  with  which  this  can  be  done  and  its  ef- 
fect upon  the  engine.  Nearly  every  carburetor 
is  provided  with  a  "flushing"  or  "priming" 
pin  by  means  of  which  the  float  can  be  de- 
pressed so  that  the  gasoline  chamber  will  be 
filled  rapidly  to  a  point  above  its  normal  level. 
This  is  useful  in  starting,  as  the  desired  rich 
mixture  is  quickly  obtained  without  an  undue 
amount  of  cranking.  If  the  carburetor  flushes 
easily,  it  is  evident  that  there  is  no  serious 
stoppage  in  the  pipe.  If  this  easy  flushing  is 
followed  by  good  running  on  the  part  of  the 
motor,  and  if  this,  in  turn,  is  succeeded  by 
gradually-diminishing  impulses  indicating  a 
weakening  mixture,  it  is  quite  evident  that  the 
float  is  preventing  the  flow  of  the  gasoline  at 
the  proper  time. 


CARBURETORS  107 

In  addition  to  the  flush  pin  found  on  car- 
buretors, many  are  provided  with  other  de- 
vices to  render  starting  easy.  It  is  well  known 
that  a  "  high-test "  gasoline,  such  as  a  76,  will 
vaporize  more  easily  than  will  one  of  a  lower 
degree  of  specific  gravity.  Also,  every  mo- 
torist has  had  impressed  upon  him  the  fact 
that  heat  aids  in  the  vaporization  of  gasoline. 
If  we  try  to  start  a  motor  on  a  cold  morning 
with  a  low-grade  gasoline,  such  as  the  60-  or 
62-degree  fuel  now  generally  obtained,  we 
know  that  a  rag  dipped  in  hot  water  and  wound 
around  the  carburetor  will  help  matters. 

To  enable  low  grades  of  fuel  to  be  properly 
vaporized  under  all  running  conditions,  many 
carburetors  are  provided  with  a  water  jacket 
surrounding  the  vaporizing  chamber.  This 
jacket  is  connected  with  the  cooling  system  of 
the  motor,  and  the  hot  water  surrounding  the 
chamber  so  warms  the  interior  that  vaporiza- 
tion is  greatly  facilitated.  Some  of  these  sys- 
tems are  provided  with  a  shut-off  cock  by 
means  of  which  the  carburetor  may  be  opera- 
ted with  hot  water  in  the  jackets,  or  not,  as 
desired. 

Other  carburetors  employ  a  jacket  surround- 
ing the  exhaust  pipe  of  the  motor  and  con- 
nected with  the  vaporizing  chamber.  The  air 


108    THE  GASOLINE  MOTOR 

is  heated  by  the  hot  exhaust  pipe  as  it  is  sucked 
into  the  carburetor,  and  this  also  facilitates 
the  vaporization  of  the  fuel.  Some  car- 
buretors are  provided  with  both  jacket  sys- 
tems, while  others  have  neither,  but  whatever 
design  is  installed,  the  best  results  will  be  ob- 
tained if  cold  air  is  used  after  the  motor  is 
once  started.  Cold  air  is  more  "  concen- 
trated "  and  contains  a  greater  amount  of 
oxygen  per  cubic  foot  than  does  air  that  has 
been  expanded  by  heat,  and  consequently  many 
carburetors  are  provided  with  a  means  of  turn- 
ing off  the  hot  air  after  the  motor  is  started. 

The  higher  the  degree  of  specific  gravity  of 
a  fuel  on  the  Baume  scale,  the  more  volatile 
will  it  be,  and  consequently  a  68°  gasoline  will 
vaporize  more  easily  and  give  more  power 
than  will  a  60°  or  62°  fuel.  72°  gasoline  is 
often  used  in  races,  but  the  average  motorist 
does  not  get  better  than  64° — and  he  is  some- 
times lucky  to  obtain  fuel  of  that  specific 
gravity.  A  hydrometer,  or  specific  gravity 
tester,  is  a  convenient  instrument  for  the  aver- 
age motorist  to  own,  and  with  it  he  may  tell 
exactly  what  grade  of  fuel  he  is  paying  for. 
The  Baume  scale,  by  which  all  gasoline  is 
tested,  reads  in  degrees,  and  the  specific  gravity 
is  obtained  by  observing  the  depth  to  which  the 


CARBURETORS  109 

hydrometer  sinks  in  the  liquid.  This  instru- 
ment resembles  somewhat  a  glass  thermometer, 
and  is  so  graduated  that  the  deeper  it  sinks  in 
a  liquid,  the  higher  will  be  the  reading  on  its 
scale. 

Water  in  the  fuel  is  an  annoyance  that  is 
often  encountered  by  the  automobilist  and  the 
motor  boatman,  and  this  will  make  its  pres- 
ence known  by  causing  the  motor  to  skip  when 
all  adjustments  and  connections  seem  to  be  in 
perfect  condition.  Water  is  much  heavier 
than  gasoline  and  has  no  affinity  for  it,  and 
consequently,  as  it  sinks  to  the  bottom  of  the 
tank,  a  few  drops  in  a  large  amount  of  gasoline 
will  cause  trouble  by  passing  out  through  the 
needle  valve  at  intermittent  intervals  and  form- 
ing an  unexplosive  mixture. 

The  presence  of  the  water  in  the  fuel  may 
be  detected  easily  without  the  use  of  a  hydro- 
meter by  drawing  some  gasoline  from  the  bot- 
tom of  the  tank  into  a  tin  or  white-enameled 
cup.  If  water  is  present,  it  may  be  seen  in  the 
form  of  small  globules  in  the  bottom  of  the 
cup.  If  the  contents  of  the  cup  are  poured 
over  a  flat  surface  so  that  the  liquid  may  be 
allowed  to  spread,  the  gasoline  will  be  seen  to 
cover  a  large  surface  and  evaporate  quickly, 
while  the  water  will  seem  to  remain  in  the  glob- 


110    THE  GASOLINE  MOTOR 

ules  unevaporated  for  some  time  after  the 
gasoline  has  disappeared.  This  latter  test  will 
sometimes  show  the  presence  of  water  when 
none  can  be  discerned  in  the  bottom  of  the  cup 
before  the  contents  are  poured  out  on  the  flat 
surface. 

The  practice  of  "  doping "  the  fuel  tank  by 
adding  to  the  gasoline  ether  or  some  other 
highly  volatile  liquid  is  not  to  be  recommended 
to  the  average  motorist.  A  few  ounces  of 
ether  or  chloroform  added  to  the  fuel  will 
form  a  more  volatile  and  consequently  more 
powerful  mixture,  but  unless  the  greatest  care 
is  taken,  the  motor  is  liable  to  be  completely 
ruined  by  such  a  procedure.  Numerous  cases 
are  on  record  in  which  cylinder  heads  have 
been  blown  off  or  castings  cracked  by  the  force 
of  some  of  the  explosions  when  too  much 
"  dope  "  has  found  its  way  into  the  mixture. 

Although  the  average  motor  gasoline  ob- 
tainable nowadays  is  hardly  all  that  could  be 
desired  as  automobile  fuel,  a  little  care  taken 
when  filling  the  tank  will  eliminate  many  of  the 
carburetor  annoyances  to  which  many  cars 
seem  to  be  subject  The  cap  of  the  tank  should 
never  be  taken  off  when  the  air  is  filled  with 
particles  of  dust  that  are  liable  to  find  their 
way  into  the  fuel,  and  care  should  be  taken  to 


CARBURETORS  111 

see  that  no  pieces  of  the  rubber  or  leather 
washer  or  packing  drop  into  the  gasoline  when 
the  cap  is  removed.  Foreign  matter  and  water 
that  may  be  in  the  gasoline  when  purchased 
may  be  removed  by  straining  the  fuel  through 
a  chamois  skin  placed  inside  of  the  funnel 
through  which  the  tank  is  filled. 


CHAPTER  VII 

LUBRICATION 

A  LUBRICANT  acts  as  a  sort  of  pacifier 
between  two  surfaces  that  would  other- 
wise move  in  contact  with  each  other. 
No  surface  can  move  in  direct  contact  with 
another  of  the  same  or  a  different  material 
without  the  generation  of  heat ;  but  the  amount 
of  heat  generated,  or  resistance  met  with,  is 
determined  by  the  nature  of  these  two  rub- 
bing surfaces.  The  oil,  or  grease,  or  whatever 
suave,  slippery  substance  is  to  be  used  as  a 
lubricant,  interposes  itself  in  a  thin  film  be- 
tween the  two  rubbing  surfaces  and  smooths 
matters  over,  as  it  were.  If  a  sufficient  amount 
of  this  mechanical  soothing  syrup  is  not  fed 
to  the  rubbing  surfaces,  the  temper  and 
temperature  of  each  will  be  raised  to  the  point 
where  they  will  "  clinch,"  and  much  time  and 
effort  may  be  required  before  harmony  can 
again  be  restored. 

Thus  it  is  actually  upon  a  film  of  lubricant 

that  a  shaft  rests,  rather  than  upon  the  bear- 
112 


LUBRICATION 

ing,  or  ubox,"  in  which  it  turns.  If  the  bear- 
ing is  set  so  tight  that  there  is  no  room  for  the 
interposition  of  an  oil  film,  the  shaft  and 
journal  will  at  once  heat.  The  greater  the 
pressure  of  the  shaft  in  its  box,  the  thicker,  or 
heavier,  should  be  the  lubricant  used,  for  a 
light  oil  would  be  squeezed  out  or  "  broken 
down"  more  easily  than  would  one  that  pos- 
sesses greater  viscosity. 

The  "  coefficient  of  friction  "  may  be  termed 
the  mechanical  "  amount  of  irritability  "  gen- 
erated when  two  surfaces  are  rubbed  together. 
Thus  if  two  metals  are  rubbed  together,  this 
figure  is  high,  and  a  large  amount  of  friction, 
or  heat,  will  be  generated.  A  metal  rubbing 
over  oil,  however — as  is  the  case  with  a  well- 
lubricated  bearing — will  arouse  but  little  re- 
sentment and  its  pathway  will  be  made  smooth 
and  easy,  for  the  coefficient  of  friction  of  these 
two  materials  is  low.  The  lower  this  figure 
can  be  kept,  the  more  easily  can  the  surfaces 
be  rubbed  over  each  other  and  the  higher  will 
be  the  efficiency  of  the  bearing. 

Apply  this  to  every  bearing  or  rubbing  sur- 
face of  a  motor,  and  we  see  that  proper  lubri- 
cation affects  not  only  the  length  of  life  of  the 
moving  parts,  but  the  ease  with  which  the  en- 
gine can  be  run  and  the  consequent  power  de- 


114    THE  GASOLINE  MOTOR 

velopment.  Thus,  a  lubricant  that  will  pre- 
vent wear  between  the  moving  parts  may  be 
supplied  to  the  bearings  and  pistons  of  a  mo- 
tor, and  under  this  condition  the  engine  might 
"last"  indefinitely;  but  this  oil  might  be  so 
viscous  or  possess  so  high  a  coefficient  of  fric- 
tion that  each  bearing  would  turn  with  diffi- 
culty and  much  effort  would  be  required  to  run 
the  motor  before  it  could  begin  to  develop 
power. 

But  the  introduction  of  oil  to  a  bearing  not 
only  reduces  the  friction  between  the  surfaces 
that  would  otherwise  move  in  contact  with 
each  other,  but  it  serves  another  very  import- 
ant purpose.  Every  properly-lubricated  por- 
tion of  a  motor  either  moves  in  a  bath  of  oil 
or  is  connected  with  an  oil  reservoir  so  that 
a  certain  amount  will  be  fed  regularly  to  the 
rubbing  surfaces.  There  is  always  some  heat 
generated  in  a  bearing,  no  matter  how  well  it 
may  be  lubricated,  and  the  continuous  flow  or 
circulation  of  the  oil  serves  to  carry  off  this 
heat  that  would  otherwise  tend  to  dry  the  lubri- 
cant if  there  were  no  fresh  supply. 

The  proper  lubrication  of  the  motor  is  even 
more  necessary  than  is  the  adjustment  of  the 
carburetor  or  the  condition  of  the  ignition  sys- 
tem. To  be  sure,  if  either  the  carburetor  or 


LUBRICATION  115 

the  ignition  system  is  out  of  order,  the  motor 
will  not  run,  but  no  actual  harm  to  the  me- 
chanism will  result  from  this  fact.  On  the 
other  hand,  a  motor  may  be  run  indefinitely 
with  a  defective  lubricating  system,  >and  no 
apparent  harm  will  result — until  the  end  of 
that  indefinite  time  arrives  and  it  is  found 
that  the  machine  is  a  fit  subject  for  a  junk  heap. 
Let  us  see  how  many  parts  of  the  motor  are 
reached  by  the  gallon  or  so  of  oil  that  we  pour 
into  the  tank.  A  six-cylinder  motor  may  have 
seven  crank  shaft  bearings;  it  will  cer- 
tainly possess  six  connecting  rods,  each  of 
which  will  be  provided  with  a  bearing  at  both 
its  large  and  small  ends — or  twelve  in  all; 
there  may  be  two  cam  shafts,  each  with  five 
bearings  and  half  a  dozen  cams;  these  will 
require,  together  with  the  magneto  and  pump 
shafts,  five  or  six  gears  in  the  forward  train; 
and  the  six  pistons  will  demand  their  share  of 
attention  from  the  lubricating  system.  Here  is 
a  grand  total  of  over  fifty  rubbing  surfaces 
on  a  large  motor,  and  the  oil  must  be 
thoroughly  and  constantly  distributed  to  each. 
Of  course,  many  smaller  motors,  provided  with 
but  a  single  cam  shaft  and  a  three-bearing 
crank  shaft,  may  possess  but  one-half  of  this 
number  of  lubricated  parts,  but  at  the  least, 


116    THE  GASOLINE  MOTOR 

the  oil  must  reach  with  unfailing  certainty  two 
dozen  vital  places  of  the  engine. 

At  some  of  these  portions,  the  movement  is 
comparatively  slow  and  the  pressure  is  not 
great.  Therefore  such  surfaces  as  the  cams  or 
valve  stem  rollers  will  demand  less  oil  than 
will  the  bearings  revolving  at  higher  speed  and 
carrying  heavier  loads.  But  it  is  the  hardest- 
worked  bearings  that  form  the  majority  of  the 
friction  surfaces  of  a  motor,  as  will  be  realized 
when  it  is  remembered  that  all  points  on  the 
circumference  of  a  three-inch  crank  shaft  bear- 
ing will  travel  at  the  approximate  rate  of  1,000 
feet  per  minute — and  these  are  the  portions 
that  also  carry  the  heaviest  load. 

But  while  the  pistons  can  hardly  be  called 
bearings  in  the  generally-accepted  layman's  de- 
finition of  the  term,  they  require  the  lion's 
share  of  the  lubricant,  and  are  the  first  por- 
tions of  the  motor  to  feel — and  show — the  ef- 
fect of  any  failure  of  the  oiling  system.  While 
in  terms  of  miles  per  hour,  the  movement  of 
the  pistons  may  not  seem  very  rapid,  the 
thousand  feet  per  minute  at  which  each 
ordinarily  travels  is  rather  a  high  rate  of  speed 
when  it  is  considered  that  it  is  entirely  a  rub- 
bing or  a  sliding  motion,  and  that  the  direction 
is  reversed  more  than  two  thousand  times  dur- 


LUBRICATION  117 

ing  each  sixty-second  period.  This  means  that 
each  piston  slides  or  rubs  within  the  cylinder 
walls  for  a  distance  of  between  two  and  three 
thousand  miles  during  an  ordinary  season. 
And  remember  that  this  is  not  a  rolling  motion, 
but  a  continuous  rubbing!  In  addition  to  this 
high-speed  rubbing,  the  pistons  are  pressed 
firmly  against  the  side  of  the  cylinders  on  each 
explosion  stroke  throughout  a  portion  of  their 
travel.  This  corresponds  to  a  heavy  pressure 
carried  by  the  rubbing  surfaces,  and  is  caused 
by  the  side  thrust  induced  by  the  angularity  of 
the  connecting  rod  as  it  overcomes  the  re- 
sistance of  the  load  through  the  crank  shaft. 

But  this  is  only  a  small  portion  of  the  diffi- 
culties that  must  be  overcome  in  cylinder  lubri- 
cation. Not  only  must  the  oil  pacify  the  rub- 
bing surfaces  and  keep  them  well  separated, 
but  it  must  remain  within  a  restricted  territory 
of  the  cylinder  walls.  Whatever  oil  reaches 
the  upper  portion  of  the  cylinder  walls  will  be 
burned  and  will  contribute  to  the  formation  of 
the  carbon  that  is  the  mortal  enemy  of  effi- 
cient running.  Large  quantities  of  oil  burned 
in  the  cylinder  will  also  form  the  dense  clouds 
of  choking  blue  smoke  that  the  health  authori- 
ties of  many  cities  have  been  investigating, 
which  have  led  to  the  enactment  of  city  ordin- 


118    THE  GASOLINE  MOTOR 

ances  making  the  driving  of  a  smoking  auto- 
mobile a  misdemeanor. 

In  view  of  the  difficulty  which  has  been  ex- 
perienced by  many  drivers  in  sufficiently  lubri- 
cating the  pistons  without  causing  the  car  to 
emit  clouds  of  smoke,  it  may  well  be  asked, 
;<  Why  cannot  an  unburnable  oil  be  used  and 
thereby  eliminate  this  trouble?"  This  is  out 
of  the  question,  for  the  mineral  oils  now  used 
are  obtained  from  petroleum  and  are  cousins 
of  kerosene,  gasoline,  benzine,  and  many  of 
the  other  highly-inflammable  liquids  that  need 
but  the  touch  of  a  match  to  burn  almost  with 
the  rapidity  of  an  explosion.  But  notwith- 
standing the  excitable  family  to  which  the 
mineral  oils  belong,  the  modern  motor  car 
lubricants  are  removed  a  sufficient  distance 
from  their  more  inflammable  relatives  to  en- 
able them  to  withstand  a  temperature  of  be- 
tween 400  and  500  degrees,  Fahrenheit.  This 
is  sufficient  heat-resisting  ability  to  enable  the 
oil  to  stay  on  the  cylinder  walls  near  the  bot- 
tom of  the  stroke,  where  it  is  most  needed; 
but  even  though  its  burning  point  could  be 
raised  to  a  degree  double  its  present  amount, 
it  could  not  withstand  the  high  temperature 
generated  in  the  top  of  the  cylinder  at  the  time 
of  the  explosion.  The  temperature  here 


LUBRICATION  119 

reaches  a  point  well  above  the  2OOO-degree 
mark,  and  were  it  not  for  the  cooling  system, 
parts  of  the  interior  of  the  cylinder  would 
probably  be  melted  by  the  continued  applica- 
tion of  this  excessive  heat. 

Any  oil,  consequently,  would  find  but  small 
opportunity  to  remain  in  its  normal  state  after 
it  once  reached  a  point  at  which  it  would  be 
exposed  to  the  heat  of  the  explosions,  and  we 
must  look  for  a  preventive  measure  other  than 
that  of  increasing  the  flash-point  or  burning- 
point  of  the  lubricant.  But  this  high  tem- 
perature does  not  exist  throughout  the  stroke, 
for  as  the  piston  descends  and  the  gas  ex- 
pands, heat  is  given  off  until  the  oil  on  the 
lower  portions  of  the  cylinder  uncovered  by 
the  piston  is  sometimes  able  to  remain  in  com- 
parative peace.  And  even  though  this  oil  re- 
maining on  the  cylinder  walls  at  the  bottom  of 
the  stroke  should  be  burned,  it  would  not  be 
present  in  sufficient  volume  to  create  the  dense 
clouds  of  objectionable  smoke.  Consequently 
it  is  the  endeavor  of  engineers  so  to  design  the 
pistons  and  lubricating  system  that  excess  oil 
will  not  be  fed  to  the  pistons  and  allowed  to 
remain  on  the  walls  after  the  former  have 
descended. 

But  an  excess  amount  of  oil  fed  to  the  cylin- 


120    THE  GASOLINE  MOTOR 

ders  will  result  in  so  much  less  harm  than  will 
an  insufficient  supply,  that  we  are  treading  on 
rather  dangerous  ground  when  we  warn  the 
amateur  to  cut  down  his  lubricant  to  the  point 
where  there  will  be  no  smoke.  As  there  are 
no  ordinances  that  absolutely  prohibit  the 
slightest  appearance  of  smoke  at  the  exhaust, 
and  as  a  faint  blue  trail  is  an  excellent  indica- 
tion that  the  motor  is  receiving  sufficient  lu- 
brication in  the  cylinders,  it  forms  a  satisfac- 
tory test  by  which  the  novice  can  determine 
the  condition  of  the  oiling  system. 

By  the  time  that  the  exhaust  gases  have 
passed  through  the  pipes  and  have  expanded 
in  the  muffler,  some  of  the  blue  smoke  may 
have  disappeared,  and  consequently  the  fact 
that  a  car  does  not  give  a  trace  of  vapor  at  its 
exhaust  should  not  necessarily  be  taken  as  an 
indication  that  the  motor  is  not  well  lubricated. 
If  the  owner  would  satisfy  himself  that  the 
cylinders  are  receiving  a  sufficient  amount  of 
oil,  he  may  open  the  individual  pet  cock  on 
each,  and  if  he  finds  there  a  faint  blue  trail  of 
smoke  at  each  explosion  in  that  cylinder,  he 
may  rest  assured  that  harmony  exists  between 
the  rubbing  surfaces  of  the  piston  and  the 
cylinder  walls. 

With  the  increase  in  the  size  and  power  of 


LUBRICATION  121 

the  automobile  motors  and  the  proportionately 
greater  number  of  parts  demanding  lubrica- 
tion, the  attention  required  from  the  driver  by 
the  oiling  system  has  been  greatly  lessened. 
Instead  of  the  necessity  of  turning  on  in- 
dividual oil  cups  whenever  the  motor  is  started, 
the  modern  driver  merely  twirls  the  starting 
crank  or  presses  the  button  of  the  self-starter, 
secure  in  the  knowledge  that  whenever  the  mo- 
tor runs,  the  lubricating  system  operates — 
provided,  of  course,  the  reservoir  is  filled  and 
there  is  no  stoppage  in  the  pipes.  The  oiling 
system  of  the  modern  motor  is  absolutely  auto- 
matic, and  if  supplied  with  a  sufficient  quantity 
of  a  good  lubricant,  it  will  perform  its  work 
with  an  absence  of  trouble  that  places  it  among 
the  greatest  improvements  of  the  engine  of  re- 
cent years. 

Individual  oil  cups  such  as  were  used  former- 
ly, have  been  eliminated  from  the  cylinders, 
and  whatever  sight-feeds  there  may  be  arc 
placed  on  the  dash  in  plain  view  of  the  driver. 
Instead  of  relying  upon  the  suction  of  the 
cylinders  for  the  positive  feed  to  the  piston, 
mechanically-operated  pumps  are  used  to  force 
the  oil  to  the  various  portions  of  the  motor. 
In  some  systems,  there  is  a  separate  pump  for 
each  oil  lead.  This  is  known  as  a  mechanical 


122    THE  GASOLINE  MOTOR 

oiler,  and  generally  consists  of  an  oil  tank  lo- 
cated on  the  dashboard  of  the  car — either  in 
front  of  the  driver,  or  under  the  motor  hood 
— and  connected  by  means  of  a  belt  or  gear 
with  some  shaft  of  the  motor.  The  belt  or 
gear  drives  a  shaft  to  which  is  connected  the 
plungers  of  the  various  oil  pumps  that  force 
the  oil  to  the  different  parts  of  the  motor.  Be- 
fore passing  to  the  individual  pipe,  however, 
the  oil  drops  through  a  sight-feed  connected 
with  that  lead,  and  as  all  of  these  sight-feeds 
are  mounted  in  a  row  within  plain  view  of  the 
driver,  the  condition  of  the  lubricating  system 
in  part  or  in  whole  may  be  determined  at  a 
glance. 

The  parts  of  the  motor  that  are  lubricated 
by  an  independent  feed  line  in  this  manner  may 
vary  with  different  motors.  In  general,  how- 
ever, it  may  be  said  that  it  is  seldom  that  the 
oil  is  fed  directly  to  the  piston,  but  that  the  lu- 
bricant is  first  distributed  to  the  oil  wells  in  the 
crank  case.  Here,  the  splash  of  the  cranks  as 
they  revolve  in  the  oil  is  depended  upon  to 
throw  the  lubricant  upon  the  exposed  portion 
of  the  piston  as  it  reciprocates  below  the  cylin- 
der walls.  The  sides  of  the  piston  thus 
covered  carry  the  oil  to  the  cylinder  walls. 

It  is  evident  that  if  an  excess  amount  of  oil 


LUBRICATION  123 

is  continually  carried  up  by  the  piston  to  the 
cylinder  walls,  a  certain  proportion  of  this  lu- 
bricant will  reach  the  open  space  in  which  the 
charge  is  ignited,  and  will  there  be  burned — 
with  the  attendant  formation  of  clouds  of  ob- 
jectionable smoke.  This  trouble  is  overcome 
to  a  certain  extent  in  some  motors  by  the  use 
of  a  type  of  ring  set  in  the  piston  that  prevents 
the  lubricant  from  passing  to  the  upper  portion 
of  the  cylinder;  but  all  the  oil  cannot  thus  be 
retained,  and  it  therefore  behooves  the  driver 
not  to  allow  too  great  a  quantity  to  be  fed 
to  the  crank  case  if  the  "  splash "  system  is 
used. 

The  main  bearings  on  which  the  crank  shaft 
revolves  are  generally  supplied  with  oil  by  in- 
dependent leads  from  the  oiler,  and  when  the 
above-described  system  is  used  they  may  be 
regulated  independently  of  the  splash  feed  lu- 
bricating pipes.  Excess  oil  at  the  bearings  will 
cause  no  damage,  but  each  crank  shaft  journal 
does  not  demand  as  great  an  amount  as  that 
supplied  to  a  piston  and  connecting  rod  bear- 
ing. 

Many  lubricating  systems  that  are  now  in 
popular  use  employ  but  one  pump  to  force  the 
oil  to  the  various  bearings  and  rubbing  sur- 
faces, and  regulate  the  supply  by  the  size  of  the 


124    THE  GASOLINE  MOTOR 

pipe  leading  to  each.  A  satisfactory  method 
of  overcoming  the  possibility  of  excess  oil  in 
the  cylinder  has  been  adopted  by  some  manu- 
facturers. This  consists  in  placing  a  channel, 
or  trough,  directly  under  the  lower  sweep  of 
each  connecting  rod  bearing.  Each  channel  is 
kept  filled  to  overflowing  by  a  separate  pipe 
connected  with  the  main  lead  from  the  pump, 
and  a  constant  level  is  consequently  maintained 
at  all  speeds  of  the  motor.  An  elaboration  of 
this  method  consists  in  attaching  one  end  of 
each  trough  to  a  rod  operated  in  conjunction 
with  the  throttle,  so  that  as  the  speed  of  the 
motor  increases,  the  end  of  the  channels  may 
be  tilted,  with  the  result  that  the  connecting 
rod  scoop  will  dip  deeper  into  the  lubricant. 

After  the  proper  level  in  each  trough  has 
been  reached  the  excess  oil  overflows  into  the 
bottom  of  the  crank  case.  From  here,  it  is 
again  started  on  its  way  by  the  pump  and  is 
distributed  to  the  various  bearings  and  troughs 
through  the  different  pipes  leading  from  the 
pump.  As  a  further  precaution  against  a 
smoking  exhaust,  some  designers  have  added  a 
baffle  plate  above  each  crank  case  compart- 
ment that  serves  to  reduce  the  size  of  the  open- 
ing through  which  the  oil  may  be  splashed. 
With  this  combination  of  troughs  and  baffle 


LUBRICATION 

plates  the  possibility  of  a  smoking  motor  is 
practically  eliminated. 

All  motors  are  not  so  equipped,  however, 
and  in  the  case  of  those  provided  with  the 
bona-fide  splash  system,  care  must  be  taken  to 
keep  the  separate  crank  case  compartments 
filled  to  the  proper  level.  Too  high  a  level  in 
the  crank  cases  will  cause  the  motor  to  smoke; 
while  the  supply  should  not  be  allowed  to  be- 
come so  low  that  when  the  angle  of  the  crank 
case  is  changed — as  in  ascending  a  hill — the 
lubricant  will  run  toward  the  rear  and  will  not 
be  reached  by  the  scoop  on  the  connecting  rod 
bearing.  This  latter  danger  makes  it  advisable 
to  give  this  system  plenty  of  oil  when  any  tour- 
ing is  to  be  done  through  a  hilly  district. 

In  some  lubricating  systems,  the  oil  is  sup- 
plied as  it  is  used,  and  either  is  discharged  with 
the  exhaust,  or  collects  in  the  bottom  of  the 
crank  case,  from  which  it  should  be  drained 
occasionally.  In  the  circulating  systems,  how- 
ever, which  are  now  used  on  a  majority  of  the 
cars,  the  same  oil  is  used  continuously  until  it 
becomes  "  worn  "  or  filled  with  sediment  and 
particles  of  dirt  and  other  foreign  matter. 
The  pump  used  for  maintaining  this  circulation 
may  be  either  of  the  plunger,  centrifugal,  or 
gear  type,  and  is  generally  housed  in  a  portion 


126    THE  GASOLINE  MOTOR 

of  the  crank  case.  A  strainer  is  usually  placed 
in  the  suction  end  of  this  pump  for  the  purpose 
of  removing  all  the  free  foreign  matter  from 
the  oil  before  it  is  again  started  on  its  mission 
of  lubrication.  In  these  systems,  the  oil  well 
is  generally  located  in  a  u  secondary "  bot- 
tom of  the  crank  case.  From  here  it  may  be 
drained  when  the  supply  is  to  be  renewed. 

Another  successful  system  by  which  all  the 
bearings  of  the  crank  shaft  are  positively  lu- 
bricated is  used  on  many  of  the  best  cars.  In 
this  system,  a  continuous  oil  hole  passes 
throughout  the  length  of  the  crank  shaft,  in- 
cluding its  "  arms  "  and  connecting  rod  bear- 
ings. At  each  bearing,  one  or  two  small  oil 
holes  connect  with  this  main  artery  and  extend 
radially  to  the  surface.  Oil  is  forced  into  the 
longitudinal  oil  hole  by  means  of  a  small  pump, 
and  naturally  finds  its  way  through  every  radial 
opening  to  all  the  bearings.  The  excess  may 
overflow  into  the  individual  oil  wells,  from 
which  it  will  be  splashed  upon  the  exposed  por- 
tions of  the  pistons  as  they  descend. 

It  will  be  seen  that,  no  matter  what  modern 
oiling  system  is  used,  the  same  kind  of  lu- 
bricant is  supplied  to  all  parts  of  the  motor. 
This  feature  makes  matters  much  simpler  than 
was  the  case  when  one  oil  was  used  for  the 


LUBRICATION  127 

cylinders,  another,  of  a  different  thickness, 
supplied  to  the  crank  case,  and  still  a  third 
required  for  the  gears.  By  the  old  gravity  sys- 
tems, the  flow  of  oil  depended  largely  upon  its 
viscosity,  or  thickness.  Therefore,  in  winter, 
a  thinner  oil  was  required  than  in  summer,  for 
the  more  a  lubricant  is  warmed,  the  thinner 
does  it  become — and  vice  versa.  With  the 
mechanical  force  systems  now  in  use,  however, 
practically  the  same  kind  of  oil  may  be  used 
throughout  the  year — although  many  motor- 
ists believe  that  better  results  will  be  obtained 
if  a  heavier  oil  is  used  in  summer  than  in 
winter.  The  oil  will  be  warmed  by  the  motor 
and  it  will  not  require  many  minutes  of  opera- 
tion before  a  lubricant  made  thick  by  a  low 
temperature  will  flow  freely  and  do  its  work  as 
efficiently  as  a  thinner  oil. 

But  no  matter  how  reliable  a  lubricating  sys- 
tem may  be  in  its  operation,  the  driver  must  do 
his  share  and  make  certain  that  fresh  oil  of  the 
proper  quality  is  supplied  when  needed,  and 
assure  himself  that  all  the  passages  are  free 
from  obstructions.  Negligence  on  the  driver's 
part  may  result  in  one  or  more  "stuck"  pis- 
tons that  will  either  seriously  injure  the  motor, 
or  will  put  it  out  of  commission  until  the 
trouble  can  be  remedied.  If  a  sufficient  supply 


128    THE  GASOLINE  MOTOR 

of  oil  is  not  fed  to  the  rubbing  surfaces  between 
the  piston  and  the  cylinder  walls,  a  high  degree 
of  heat  is  generated  which  will  tend  to  expand 
the  piston  until  it  grips  the  cylinder  so  closely 
that  the  former  cannot  be  moved.  In  this 
event  the  motor  will  stop  "  dead,"  and  can- 
not be  started  again  until  the  piston  has  cooled 
and  contracted  to  its  normal  size.  Even  then, 
however,  the  motor  should  not  be  run  under 
its  own  power  until  the  burned  and  gummed  oil 
has  been  removed  and  the  scored  surfaces  have 
been  cleaned.  While  this  may  best  be  done  by 
removing  the  piston — at  which  time  an  ex- 
amination for  any  badly  burned  rings  may  be 
made — this  is  not  always  possible,  and  it  may 
be  necessary  to  run  the  car  home  or  to  the  near- 
est repair  shop  before  the  proper  repairs  can 
be  made. 

In  this  case,  the  motor  should  be  turned  by 
hand  until  it  is  certain  that  the  piston  is  again 
free  in  its  cylinder.  Liberal  quantities  of  kero- 
sene oil  should  be  poured  in  through  the  spark 
plug  opening,  and  if  possible,  the  motor  should 
be  "  rocked  "  back  and  forth  by  the  flywheel  to 
give  the  kerosene  an  opportunity  to  reach  all 
parts  of  the  piston  and  rings.  The  kerosene 
will  serve  to  cut  and  remove  much  of  the  car- 
bon and  gummed  oil  and  to  make  the  way  free 


LUBRICATION 

for  the  fresh  lubricant,  which  should  be  poured 
in  liberal  quantities  into  the  cylinder  head. 
The  flywheel  should  again  be  moved  back  and 
forth  so  that  the  oil  will  reach  all  parts  of  the 
piston  surface,  and  after  this — if  the  damage 
has  not  been  too  great — the  motor  should  be 
ready  for  operation. 


CHAPTER  VIII 
COOLING 

TO  enable  the  parts  of  a  motor  to  work 
well,  there  must  be  freedom  of  motion 
between  all  that  move  in  contact  with 
each  other.  This  necessary  freedom  of  motion 
is  provided  for  to  a  certain  extent  by  proper 
lubrication,  but  this  is  not  all-sufficient.  The 
necessity  for  some  additional  friction-  and 
heat-reducing  system  can  be  better  realized 
when  it  is  understood  that  the  temperature  of 
the  explosion  in  the  cylinders  of  a  gasoline  en- 
gine is  well  over  2,600  degrees,  Fahrenheit. 
The  melting  point  of  pure  iron  is  less  than 
2,800  degrees.  Therefore  were  there  no 
escape  for  this  heat,  and  could  the  motor  be 
induced  to  run  under  these  severe  conditions, 
the  cylinders  would  soon  reach  a  temperature 
dangerously  near  the  melting  point.  Long  be- 
fore this  point  could  be  reached,  however,  the 
intense  heat  would  have  expanded  the  pistons 
so  that  they  would  become  stuck  in  their  cylin- 
ders, and  no  more  explosions  could  occur.  An 

130 


COOLING  131 

ominous  knock  in  one  or  more  of  the  cylinders, 
followed  by  a  sudden  laboring  and  final  cessa- 
tion of  operation  on  the  part  of  the  motor,  is 
sometimes  the  first  intimation  that  the  driver 
may  have  that  his  engine  is  over-heated;  but 
serious  as  a  "  stuck "  piston  may  seem,  it  is 
fortunate  that  the  motor  stops  of  its  own  ac- 
cord, for  to  continue  to  run  under  these  con- 
ditions of  constantly  increasing  heat  would  be 
to  wreak  far  more  serious  and  permanent 
damage  upon  the  moving  parts  than  the  broken 
rings  or  scored  cylinders  that  usually  result 
from  a  lack  of  lubrication  or  cooling  medium. 
A  large  amount  of  the  heat  resulting  from 
each  explosion  is  carried  out  through  the  ex- 
haust pipe  in  the  form  of  the  burned  gases, 
while  other  portions  radiate  into  the  surround- 
ing air.  These  outlets  are  not  sufficient,  how- 
ever, to  carry  away  all  the  heat  that  is  neces- 
sary to  enable  the  motor  to  run  efficiently,  for 
proper  piston  lubrication  is  exceedingly  diffi- 
cult to  obtain  at  high  temperatures.  There 
must,  therefore,  be  more  positive  and  direct 
means  for  carrying  off  this  undesired  heat,  and 
to  accomplish  this  result  every  internal  com- 
bustion motor  is  provided  with  a  cooling  sys- 
tem of  either  the  air  or  liquid  (usually  water) 
type.  Motorcycle  power  plants  and  a  few  of 


132    THE  GASOLINE  MOTOR 

the  small  and  medium-sized  automobile  en- 
gines employ  the  air-cooling  system;  the  great 
majority  of  automobile  engines,  stationary 
plants,  and  marine  motors  use  water  as  the 
cooling  medium. 

Let  us  consider  first  the  air-cooled  system. 
The  area  presented  by  the  outside  of  a  smooth 
cylinder  is  not  large  enough  to  enable  suffi- 
cient radiation  to  take  place.  That  is,  the  heat 
is  concentrated  on  a  comparatively  small  sur- 
face, and  this  is  much  more  difficult  to  keep 
cool  than  is  the  same  amount  of  heat  distri- 
buted over  a  greater  area — for  the  cylinder 
will  be  exposed  to  a  larger  quantity  of  fresh 
air  in  the  latter  case.  Therefore  many  air- 
cooled  engines  are  provided  with  a  series  of 
grooves  and  flanges  on  the  outer  surface  of  the 
cylinder.  The  heat  is  conducted  to  all  parts 
of  this  surface — flanges  as  well  as  grooves — 
and  the  area  of  the  surface  that  is  exposed  to 
the  cooling  air  is  greatly  increased  thereby. 

These  grooves  and  flanges  may  extend  cir- 
cumferentially  around  the  cylinder,  as  is  the 
case  with  many  motorcycle  engines,  or  they 
may  extend  longitudinally.  Another  form  of 
air-cooling  system  consists  of  pins  or  spines 
projecting  radially  from  the  surface  of  the 
cylinder.  The  motion  of  the  car  through  the 


COOLING  133 

air  is  generally  sufficient  to  create  a  circulation 
of  the  cooling  medium,  but  in  order  that  this 
circulation  may  continue  while  the  car  is  at 
rest  a  high-speed  fan  is  provided  that  draws 
the  air  from  the  front  toward  the  rear  of  the 
motor.  This  serves  also  to  supplement  the  air 
circulation  produced  by  the  motion  of  the  car, 
and  keeps  the  motor  much  cooler  than  would 
be  the  case  were  the  machine  run  without  the 
fan.  This  fan  is  generally  attached  to  a 
bracket  at  the  front  of  the  motor,  and  is  driv- 
en either  by  a  belt  or  geared  shaft.  In  some 
designs,  however,  the  fan  blades  are  included 
in  the  flywheel  at  the  rear  of  the  motor  and 
the  air  is  thus  sucked  over  the  cylinders. 

One  of  the  most  effective  air-cooling  sys- 
tems for  use  on  an  automobile  motor  consists 
of  the  above-mentioned  longitudinal  flanges 
and  grooves  enclosed  in  a  thin  jacket  or  casing 
surrounding  each  cylinder.  These  jackets  are 
open  at  the  top  and  bottom  of  the  cylinders, 
and  connect  with  large  pipes,  or  troughs, 
through  which  air  is  forced.  The  trough  into 
which  the  top  of  the  jacket  spaces  open  is  con- 
nected with  the  discharge  end  of  a  large  fan. 
The  air  is  thus  driven  into  the  top  trough, 
through  each  jacket,  and  into  the  lower 
trough,  the  farther  termination  of  which  is  con- 


134    THE  GASOLINE  MOTOR 

nected  with  the  suction  end  of  a  fan  included  in 
the  flywheel.  The  two  fans  serve  to  set  up  a 
rapid  circulation  of  air  which,  by  means  of  the 
troughs  and  jackets,  is  concentrated  upon  the 
surfaces  of  the  grooves  and  flanges  of  each 
cylinder  and  none  is  wasted  on  parts  of  the  mo- 
tor that  it  is  unnecessary  to  cool.  Furthermore, 
the  rear  cylinders  receive  as  much  air  as  do  the 
forward  ones,  for  the  trough  serves  to  distri- 
bute the  circulation  equally  along  the  grooves 
and  flanges  of  each. 

Inasmuch  as  the  heat  from  an  air-cooled  mo- 
tor is  radiated  directly  into  the  current  of  air 
itself,  the  surface  is  very  susceptible  to  tem- 
perature changes  from  the  interior.  Thus,  if 
the  car  is  run  for  a  great  distance  on  the  low 
gear,  and  the  cylinders  become  hot  in  conse- 
quence, a  larger  amount  of  heat  will  im- 
mediately be  radiated  from  the  cooling  sur- 
faces than  is  the  case  when  the  motor  is  run- 
ning slowly.  A  "  coast "  down  a  short  hill, 
however,  will  serve  to  cool  the  motor  rapidly, 
for  if  the  engine  is  run  from  the  momentum 
of  the  car  with  the  spark  turned  off,  cool  air 
will  be  drawn  into  the  cylinders,  and  this,  in 
addition  to  the  circulation  of  cold  air  on  the 
outside,  will  reduce  the  temperature  of  the  en- 
gine rapidly.  This  is  a  feature  of  the  opera* 


COOLING  135 

tion  of  an  air-cooled  motor  that  is  not  pos- 
sessed to  so  large  an  extent  by  those  of  the 
water-cooled  type. 

It  is,  perhaps,  hardly  accurate  to  apply  the 
term  "  water-cooled  "  to  the  ordinary  type  of 
automobile  motor.  Water  is  merely  the 
medium  that  transfers  the  heat  from  the  cylin- 
ders to  the  cooling  surface  of  the  radiator. 
As  air  is  used  to  cool  this  heated  water,  we  see 
that  the  only  difference  between  the  two  sys- 
tems lies  in  the  point  of  application  of  the 
actual  heat-absorbing  medium — which  is  air  in 
both  cases.  Thus  in  the  air-cooled  motor  the 
air  is  carried  directly  to  the  surfaces  to  be 
cooled;  while  in  the  other  type,  the  heat  is 
transferred  by  means  of  the  water  to  the  point 
where  it  may  be  effectually  discharged  into  the 
air. 

Each  cylinder  of  a  water-cooled  motor  is 
surrounded  by  a  space  known  as  the  water 
jacket.  This  space  is  generally  cast  with  the 
cylinder,  although  in  some  designs  of  motors 
the  jackets  are  formed  by  the  subsequent  ap- 
plication of  a  copper  casing  that  serves  to  re- 
tain the  water.  The  water  jackets  are  con- 
nected with  each  other  by  means  of  piping  and 
water-tight  joints  so  that  the  water  will  pass 
successively  from  one  to  the  other.  If  the 


136    THE  GASOLINE  MOTOR 

water  remained  in  these  spaces,  it  would  soon 
be  warmed  to  a  temperature  far  above  the  boil- 
ing point,  steam  would  be  formed,  a  high  pres- 
sure generated,  and  infinite  harm  would  result 
— both  to  motor  and  to  passengers.  The  pip- 
ing, however,  does  not  end  with  the  connec- 
tions between  the  cylinders,  but  extends  to  and 
from  the  radiator. 

This  radiator  is  a  large,  perforated  structure 
placed  either  forward  of  the  motor  to  form  the 
end  of  the  bonnet-covering,  or  in  front  of  the 
dash  between  it  and  the  rear  cylinder  of  the 
engine.  The  radiator  is  a  mass  of  small  cellu- 
lar or  tubular  passages,  each  one  of  which  pos- 
sesses an  exceedingly  large  outer  surface  in 
proportion  to  the  amount  of  water  that  it  can 
contain.  When  the  hot  water  reaches  the 
radiator  it  is  distributed  to  these  many  cells  or 
tubes,  and  is  thus  spread  over  a  large  cooling 
surface.  A  large  fan  is  usually  located  di- 
rectly behind  the  radiator,  and  as  this  serves  to 
draw  the  air  rapidly  through  the  openings  be- 
tween the  cells  or  tubes,  cooling  is  greatly 
facilitated. 

There  are  several  types  of  radiators  in  gen- 
eral use.  Some  consist  of  a  number  of  flat  cells 
placed  in  such  a  manner  that  regular-shaped 
air  openings  will  be  formed.  Each  side  of  each 


COOLING  137 

flat  water  cell  abuts  on  an  air  passage.  Such 
a  radiator  is  known  as  the  honeycomb,  or  cellu- 
lar, the  former  term  being  applied  to  those 
whose  cells  resemble  a  honeycomb.  The  tubular 
radiator  consists  of  a  number  of  vertical,  par- 
allel tubes  through  which  the  water  passes,  and 
which  are  placed  a  sufficient  distance  apart  to 
provide  ample  air  passages  between  them. 
Each  tube  is  covered  at  frequent  intervals  with 
fluted,  circular  flanges  that  serve  to  increase 
the  radiating  surface  in  much  the  same  manner 
as  do  the  grooves  and  flanges  on  the  cylin- 
ders of  the  air-cooled  motor.  All  air  passages 
in  any  radiator  extend  directly  through  the 
width  of  the  radiator,  while  the  water  circu- 
lates from  top  to  bottom  in  a  vertical  direction. 
The  reason  for  this  circulation  of  the  water 
will  be  apparent  if  we  call  to  mind  a  bit  of  our 
elementary  physics.  When  water  is  heated,  it 
expands  and  rises,  and  for  this  reason,  we  al- 
ways find  the  surface  of  the  water  in  a  tea- 
kettle warmer  than  is  that  at  the  bottom — al- 
though the  latter  is  closer  to  the  fire.  As  the 
water  is  circulated  through  the  radiator,  it  is 
cooled  by  the  passage  of  the  large  amount  of 
air  through  the  openings  between  the  cells  or 
tubes.  The  water  thus  cooled  sinks  to  the  bot- 
iom  of  the  radiator  and  is  replaced  by  the 


138    THE  GASOLINE  MOTOR 

water  just  heated  by  the  motor.  The  cooled 
water  is  conducted  to  the  bottom  portion  of 
the  end  cylinder,  and  passes  to  the  others  in 
succession,  gradually  rising  as  it  is  heated,  un- 
til it  is  again  forced  to  the  radiator  at  the  top. 

There  are  two  methods  of  circulating  the 
water  through  the  cylinder  jackets  and  ra- 
diator. The  most  common  method  consists  of 
the  introduction  of  a  pump  in  the  lower  por- 
tion of  the  circulating  system.  In  the  case  of 
automobile  motors,  this  pump  is  driven  by 
gears  connected  with  the  crank  shaft  of  the  en- 
gine. Such  a  pump  will  be  either  of  the  gear 
or  centrifugal  type,  and  will  suck  the  cooled 
water  from  the  lower  portion  of  the  radiator, 
and  force  it  through  the  jackets.  The  second 
method  is  known  as  the  thermo-syphon  system 
because  the  circulation  is  automatic  and  de- 
pends upon  the  cooling  of  the  water  in  the  ra- 
diator. When  the  cooled  water  sinks,  a  syphon 
action  is  formed  that  tends  to  draw  the  hot 
water  from  the  cylinder  jackets,  and  the  auto- 
matic circulation  will  thus  continue  as  long  as 
the  successive  heating  and  cooling  take  place. 

Inasmuch  as  the  pump  is  driven  by  the  crank 
shaft  of  the  engine,  its  speed  will  be  pro- 
portional to  that  of  the  motor.  The  same 
holds  true  of  the  fan  that  serves  to  draw  the 


COOLING  139 

air  through  tEe  radiator.  It  will  thus  be  seen 
that  both  the  water  and  the  air  are  forced  at  a 
more  rapid  rate  when  the  motor  runs  at  high 
speed,  and  that  therefore  the  extra  heat  gen- 
erated by  the  more  frequent  explosions  in  the 
cylinders  will  be  counteracted  to  a  certain  ex- 
tent. The  increased  number  of  explosions  and 
the  higher  speed  at  which  the  fan  turns  also 
cause  quicker  heating  and  cooling  of  the  water 
by  the  thermo-syphon  system,  thus  forming  a 
more  rapid  circulation.  Inasmuch  as  the  force 
exerted  upon  the  water  by  its  cooling  and  heat- 
ing is  not  as  great  as  that  formed  by  a  high- 
speed and  efficient  pump,  the  pipes  and  connec- 
tions of  the  thermo-syphon  system  must  be  of 
ample  size  in  order  to  keep  the  resistance  to 
the  passage  of  the  water  as  low  as  possible. 
Care  must  also  be  taken  in  the  design  of  this 
system  so  to  construct  and  connect  the  pipes 
and  jackets  that  the  hot  water  will  be  allowed 
to  rise  and  the  cool  to  descend,  and  thus  to 
make  possible  the  syphon  conditions  on  which 
principle  the  circulation  is  based. 

The  ability  of  the  radiator  to  carry  off  the 
heat  from  the  water  depends  upon  the  rapidity 
with  which  the  air  passes  through  the  passages 
provided  for  the  purpose.  The  amount  of  air 
passing  through  is  determined  by  the  speed  of 


140    THE  GASOLINE  MOTOR 

the  suction  fan  and  the  rapidity  of  travel  of 
the  car  itself  against  the  wind.  It  has  been 
shown  that,  when  the  motor  runs  at  a  high 
number  of  revolutions,  the  fan  turns  faster 
and  the  rapidity  of  circulation  is  increased. 
But  if  the  car  itself  does  not  increase  its  speed 
in  proportion  to  the  higher  revolutions  of  the 
motor,  the  maximum  amount  of  air  will  not  be 
forced  through  the  radiator  passages,  and  the 
excess  heat  will  not  be  carried  off  entirely  from 
the  cylinders.  This  is  a  condition  that  prevails 
when  the  motor  is  run  on  low  gear.  The  speed 
of  the  motor  is  increased,  while  that  of  the  car 
is  reduced;  additional  heat  is  generated  in  the 
cylinders,  but  the  speed  of  the  air  is  not  in- 
creased in  proportion.  Therefore  a  motor 
that  is  driven  a  long  distance  on  the  low  gear 
will  have  a  tendency  to  overheat 

Water  under  atmospheric  pressure  cannot 
be  brought  to  a  temperature  above  212  de- 
grees Fahrenheit  without  being  converted  into 
steam.  Therefore,  when  the  heat  from  a 
water-cooled  motor  cannot  be  carried  away 
sufficiently  fast,  the  water  in  the  circulating 
system  will  begin  to  boil.  As  long  as  water  re- 
mains in  the  jackets,  the  temperature  of  these 
spaces  cannot  well  rise  above  212  degrees,  and 
consequently  there  is  small  danger  that  a 


COOLING 

water-cooled  motor  will  become  overheated  to 
the  point  at  which  the  pistons  will  "  seize  "  in 
the  cylinders.  The  moment  the  water  in  the 
circulating  system  begins  to  boil,  however,  ex- 
ceedingly rapid  evaporation  naturally  takes 
place,  and  the  water  will  soon  entirely  disap- 
pear in  the  form  of  steam  and  vapor.  To  run 
the  motor  under  these  conditions  will  mean  that 
pistons  and  rings  will  soon  become  stuck  in 
their  cylinders,  although  liberal  quantities  of 
oil  will  sometimes  delay  this  inevitable  result. 

But  even  when  the  cooling  water  is  not 
brought  to  the  boiling  point  there  is  a  vapor 
that  is  constantly  dispelled  from  it  whenever  its 
temperature  is  brought  above  that  of  the  air. 
The  water  system  of  an  automobile  must  there- 
fore be  replenished  at  irregular  intervals,  de- 
pending upon  the  amount  and  nature  of  the 
running  to  which  the  car  has  been  subjected. 
The  older  cars  were  provided  with  an  extra 
water  tank,  generally  located  under  the  seat, 
and  connected  directly  with  the  water  jackets 
and  the  radiator.  The  usual  water-cooling 
system  of  the  present-day  car,  Eowever,  is  self- 
contained — that  is,  there  is  no  separate  tank 
for  the  storage  of  the  water.  The  water  is 
poured  into  the  top  of  the  radiator,  and  from 
this  high  point  it  reaches  every  part  of  the  cir- 


142    THE  GASOLINE  MOTOR 

culating  system.  Whenever  the  radiator  will 
accommodate  a  couple  of  quarts,  or  more,  it  is 
well  to  fill  it,  for  too  much  water  cannot  be  used 
on  the  modern  design  of  cooling  system.  It  is 
true  that  a  motor  runs  at  its  highest  efficiency 
when  its  temperature  is  as  great  as  that  at 
which  proper  lubrication  of  the  pistons  can  be 
obtained — for  a  gasoline  engine  is  a  "  heat  en- 
gine," and  the  greater  its  unnecessary  heat 
losses,  the  less  will  be  the  power  developed  by 
it.  But  a  motor  cannot  be  kept  at  the  proper 
temperature  by  reducing  the  amount  of  cooling 
water  in  its  circulating  system.  The  best 
method  is  to  lessen  the  rapidity  with  which  the 
water  is  cooled,  and  this  may  be  accomplished 
by  placing  a  leather  flap,  a  cardboard,  or  other 
obstruction  over  a  portion  of  the  radiator  to 
reduce  the  number  of  openings  through  which 
the  air  may  pass.  It  should  only  be  necessary 
to  do  this  in  the  coldest  weather,  however,  for 
the  cooling  system  of  every  motor  is  designed 
to  maintain  the  proper  temperature  on  all  ex- 
cept the  hottest  or  coldest  days. 

It  has  been  stated  in  a  preceding  paragraph 
that  continued  running  on  the  low  gear  is  the 
most  frequent  cause  of  overheating  a  motor. 
This  is  true,  but  it  is  not  the  only  cause.  Ob- 
structions in  the  circulating  system  that  reduce 


COOLING  143 

the  flow  of  water  will  have  this  effect,  as  will 
also  deposits  on  the  interior  of  the  cylinders 
that  serve  to  prevent  the  proper  transfer  of 
heat  to  the  water  in  the  jacket  spaces.  Re- 
moval of  the  carbon  will  remedy  the  latter 
trouble,  but  to  clear  out  the  circulating  sys- 
tem is  more  or  less  of  a  complicated  matter. 
Stoppage  in  the  pipes  or  radiator  cells  may  be 
caused  by  a  lime  deposit  from  "  hard  "  water 
that  may  have  been  used  in  the  circulating  sys- 
tem. There  are  preparations  intended  to  re- 
move this  deposit,  but  such  should  not  be  used 
without  first  advising  with  the  maker  of  the  car 
or  an  experienced  repair  man.  A  series  of  bat- 
tered cells  in  the  radiator  may  reduce  the  num- 
ber of  cooling  spaces  that  should  be  traversed 
by  the  water,  and  thus  the  hot  water  cannot  be 
distributed  over  as  great  an  air  area  as  is  nec- 
essary to  maintain  the  motor  at  the  proper 
temperature.  Such  a  condition  will  be  appar- 
ent from  a  marked  difference  in  temperature  be- 
tween the  affected  portion  of  the  radiator  and 
the  remainder.  If  a  deposit  has  been  formed 
on  a  certain  series  of  cells,  or  if  they  have  been 
obstructed  in  any  other  manner,  the  hot  water 
cannot  circulate  through  this  section  of  the  ra- 
diator, and  it  will  remain  comparatively  cool. 
Water  is  a  liquid  that  remains  in  its  fluid 


144    THE  GASOLINE  MOTOR 

stage  only  through  a  temperature  range  of  180 
degrees — at  atmospheric  pressure.  At  212  de- 
grees it  boils  and  turns  to  vapor,  while  at  32 
degrees  it  freezes  and  becomes  a  solid.  In 
neither  of  these  stages  does  it  form  a  desirable 
cooling  medium  for  a  gasoline  motor.  Of  the 
two,  however,  its  solid  stage  is  the  more  harm- 
ful to  the  motor.  Not  only  will  it  cease  to  flow 
when  it  becomes  ice,  but  the  expansion  of  the 
water  during  the  formation  of  the  solid  is 
liable  to  burst  its  retainer — whether  it  be  the 
cells  of  the  radiator,  the  pump,  pipes,  or  even 
the  cylinder  walls  themselves.  It  is  the  ra- 
diator that  is  the  most  liable  to  suffer  from 
such  a  cause,  however,  for  each  cell  contains  so 
small  an  amount  of  water  that  the  liquid  will 
be  brought  to  the  freezing  point  before  the 
larger  volume  in  the  jacket  spaces  approaches 
this  temperature.  Of  course  the  water  will  be 
kept  well  above  the  freezing  point  when  the 
motor  is  running,  and  it  is  only  when  the  ma- 
chine has  stood  idle  for  several  hours  that  care 
must  be  taken  to  prevent  the  formation  of  ice 
in  the  circulating  system. 

Aside  from  keeping  the  car  in  a  warm  place 
whenever  the  motor  is  to  be  at  rest  more  than 
two  hours,  there  is  only  one  method  of  prevent- 
ing the  cooling  water  from  freezing,  and  that 


COOLING  145 

is  by  the  introduction  of  some  chemical  that 
lowers  the  point  at  which  the  liquid  will  turn 
to  a  solid.  There  are  several  ingenious  heaters 
available  that  are  attached  to  the  circulating 
pipes  and  that  serve  to  keep  all  of  the  jacket 
water  warm;  the  use  of  these  producing  the 
same  conditions  as  though  the  car  were  kept 
in  an  artificially-heated  garage. 

One  of  the  most  common  liquids  used  in  the 
cooling  water  to  prevent  freezing  is  alcohol. 
If  equal  parts  of  wood  alcohol  and  water  are 
used  in  the  cooling  system,  the  resulting  mix- 
ture will  not  freeze  until  it  reaches  a  tempera- 
ture colder  than  25  degrees  below  zero.  A 
weaker  mixture — one  having  25  per  cent,  of 
wood  alcohol — will  freeze  at  about  zero,  and 
it  therefore  depends  upon  the  prevailing  cold- 
weather  temperature  as  to  the  proper  propor- 
tion that  should  be  used.  It  must  be  remem- 
bered that  the  boiling  point  of  alcohol  is  much 
lower  than  is  that  of  water,  and  that  therefore 
a  mixture  that  will  not  freeze  in  exceedingly 
cold  weather  is  liable  to  boil  away  on  the  first 
moderate  day  on  which  the  car  is  run.  The 
above-mentioned  50  per  cent,  mixture  of  wood 
alcohol  and  water  will  boil  at  135  degrees, 
while  the  25  per  cent,  solution  will  withstand  a 
temperature  40  degrees  higher  before  it  is 


146    THE  GASOLINE  MOTOR 

transformed  into  vapor.  As  the  lower  tem- 
perature will  be  reached  easily  if  the  motor  is 
run  for  some  time  in  comparatively  moderate 
weather,  it  will  be  seen  that  the  stronger  mix- 
ture should  be  used  only  where  winters  are 
very  severe.  It  must  also  be  borne  in  mind 
that,  as  alcohol  boils  more  readily  than  does 
water,  it  follows  that  it  will  evaporate  more 
easily,  as  well.  Therefore,  in  order  to  main- 
tain a  uniform  proportion  of  wood  alcohol  to 
water,  the  former  should  be  replenished  more 
often  than  is  the  latter. 

Glycerine  is  another  substance  that  is  often 
mixed  with  the  cooling  water  to  prevent  the 
latter  from  freezing.  A  50  per  cent,  mixture 
of  this  and  water  has  a  freezing  point  of  about 
zero,  or  slightly  lower,  and  boils  at  practically 
the  same  temperature  as  water — 210  degrees. 
Combinations  of  wood  alcohol  and  glycerine 
may  be  used — equal  parts  of  each  being  the 
usual  proportion — and  thus  various  freezing 
and  boiling  points  may  be  obtained. 

The  radiator  is  one  of  the  most  delicate 
parts  of  the  motor  car's  construction,  and  yet 
it  is  the  most  exposed  to  flying  sticks  and  stones 
that  may  be  thrown  up  by  the  rapid  travel  of 
the  car.  The  car  owner  may  do  well  to  follow 
the  practice  of  many  racing  drivers  who  place 


COOLING  147 

a  heavy  wire  mesh  screen  in  front  of  the  ra- 
diator as  a  protection  against  obstacles  that 
may  be  struck  by  the  front  of  the  car.  It 
would  seem  that  sticks  and  stones  would  be 
thrown  toward  the  rear  of  the  car,  and  would 
therefore  avoid  the  radiator  by  a  wide  margin, 
but  experience  has  proved  that,  at  high  speed, 
such  loose  pieces  are  frequently  forced  for- 
ward and  are  run  into  by  the  front  of  the  car. 


CHAPTER  IX 

TWO-CYCLE  MOTORS 

THERE  has  always  been  a  strong  pre- 
judice in  favor  of  the  four-cycle  motor 
for  the  power  plant  of  the  gasoline 
automobile.  This  may  be  due  to  the  fact  that 
designers  have  spent  most  of  their  time  and 
energy  on  the  development  of  this  engine,  and 
that  therefore  the  two-cycle  type  has  not  yet 
been  sufficiently  "  tried  out "  in  the  motor  car 
to  enable  us  to  judge  fairly  as  to  its  real  merits. 
Certain  it  is  that  in  the  few  instances  in  which 
the  two-cycle  motor  has  been  used  as  an  auto- 
mobile power  plant,  the  results  have  been 
highly  satisfactory,  and  the  present  vogue  of  the 
four-cycle  motor — with  well  over  98  per  cent, 
of  the  automobiles  now  made  adhering  to  this 
type — is  largely  due  to  popular  prejudice  in  its 
favor. 

As  has  been  described  in  the  first  chapter 
of  the  present  volume,  the  four-cycle  motor 
devotes  a  separate  stroke  to  each  of  the  events 
of  expansion,  scavenging  or  expulsion  of  the 

148 


TWO-CYCLE   MOTORS       149 

burned  gases,  suction,  and  compression.  The 
two-cycle  motor,  on  the  other  hand,  devotes  but 
two  strokes  to  these  four  events,  and  there  is 
therefore  an  explosion  twice  as  often  in  the 
two-cycle  engine  cylinder  as  is  the  case  with 
the  four-cycle  type.  But  in  lieu  of  the  suction 
stroke  of  the  four-cycle  motor,  there  must  be 
some  method  of  forcing  the  charge  into  the 
cylinder  of  the  two-cycle  engine.  The  base,  or 
compartment  below  the  piston,  in  which  the 
crank  revolves,  is  used  for  this  purpose.  As 
the  piston  travels  upward  on  its  compression 
stroke,  a  partial  vacuum  is  formed  in  the  base, 
and  if  a  passage  is  opened  between  this  com- 
partment and  the  carburetor,  the  charge  will 
be  sucked  in. 

All  outside  connections  with  the  base  are 
tightly  closed  on  the  down-stroke  of  the  pis- 
ton, and  consequently  the  recently-inhaled 
charge  will  be  compressed,  ready  for  its  en- 
trance into  the  cylinder  above  the  piston  as 
soon  as  the  connecting  passage  is  opened.  This 
passage  is  opened,  as  has  already  been 
described,  at  the  bottom  of  the  stroke  and  the 
compressed  charge  rushes  in  and  fills  the  space 
in  the  cylinder  that  at  that  time  is  being  vacated 
by  the  exhaust  gases. 

The  majority  of  two-cycle  motors  are  made 


150    THE  GASOLINE  MOTOR 

without  any  valve  mechanism,  the  opening  and 
closing  of  the  passages  being  entirely  automa- 
tic. These  passages  are  cast  with  the  engine 
rand  lead  into  the  cylinder  through  openings  in 
the  walls  called  "  ports."  The  opening  lead- 
ing from  the  cylinder  to  the  exhaust  pipe,  or 
exhaust  port,  is  placed  near  the  bottom  of  the 
stroke  so  that  it  is  covered  by  the  piston,  ex- 
cept at  the  lower  extremity  of  the  travel  of  the 
latter.  Just  below  the  exhaust  port,  and  on 
the  opposite  side  of  the  interior  of  the  cylin- 
der, is  placed  the  intake  port,  or  opening  of 
the  passage  connecting  the  cylinder  with  the 
base. 

Now,  as  the  piston  is  forced  downward,  it 
uncovers  the  exhaust  port  and  an  easy  means 
of  escape  is  furnished  for  the  burned  gases. 
Immediately  after  this,  the  intake  port  on  the 
opposite  side  is  uncovered  by  the  still-descend- 
ing piston,  and  the  previously  compressed 
charge,  which  is  only  awaiting  the  opportunity 
in  the  tase,  "  blows  "  in.  The  exhaust  gases 
are  still  escaping  when  this  happens,  and  there- 
fore it  is  necessary  to  prevent  the  incoming 
charge  from  passing  directly  across  the  top  of 
the  piston  and  out  through  the  exhaust  port 
before  use  has  been  made  of  its  explosive  qual- 
ities, 


TWO-CYCLE   MOTORS       151 

Consequently,  to  keep  it  in  its  proper  path, 
a  baffle  plate  is  attached  to  the  top  of  the  pis- 
ton which  serves  to  deflect  the  incoming  charge 
toward  the  top  of  the  cylinder,  and  this  not 
only  prevents  the  loss  of  the  mixture,  but  also 
furnishes  a  blast  of  air  that  helps  to  blow  out 
the  burned  gases.  On  the  return  of  the  piston 
to  the  top  of  its  stroke,  it  first  passes  over 
the  intake  port  and  then  covers  the  exhaust 
port,  effectually  closing  both  and  preventing 
the  escape  of  the  charge  during  compression. 
While  this  is  going  on,  it  must  be  remembered, 
the  piston  is  forming  the  partial  vacuum  in  the 
base,  which  serves  to  draw  in  the  charge  for 
the  succeeding  explosion. 

If  the  charge  is  drawn  directly  into  the  base 
from  the  carburetor,  a  check  valve  must  be 
used'  in  the  pipe  connecting  the  two ;  otherwise 
the  mixture  would  be  forced  back  into  the  car- 
buretor the  instant  trfe  piston  began  its  de- 
scent. A  two-cycle  motor  drawing  its  charge 
in  this  manner  is  known  as  the  two-port  type, 
for  there  are  only  the  exhaust  and  the  inlet 
ports  in  the  interior  of  the  cylinder  walls.  The 
passage  connecting  the  carburetor  with  the 
base  may  enter  at  the  bottom  of  the  cylinder, 
for  this  space  and  the  base  are  the  same  when 
the  piston  is  at  the  top  of  its  stroke.  Thus 


152    THE  GASOLINE  MOTOR 

if  this  port  is  placed  so  that  it  is  uncovered 
when  the  piston  is  at  the  top  of  its  stroke,  it 
will  admit  the  charge  to  the  base  at  a  time 
when  a  partial  vacuum  has  been  created  in  this 
compartment  by  the  upward  movement  of  the 
piston. 

This  port  is  again  covered  as  soon  as  the  pis- 
ton starts  on  its  downward  journey,  and  thus 
the  charge  is  prevented  from  escaping  until 
the  intake  port  connecting  the  base  with  the 
top  of  the  cylinder  is  opened.  Such  a  two- 
cycle  motor  is  known  as  the  three-port  type, 
and  it  will  be  seen  that  not  even  an  automatic 
check  valve  is  used  in  its  passages — and  it  is 
consequently  a  "  valveless "  motor  in  the 
liberal  interpretation  of  the  term. 

The  high  velocity  of  the  charge  recompenses 
for  the  short  time  that  the  port  is  uncovered, 
and  consequently  the  base  is  filled  with  nearly 
as  large  an  amount  of  charge  as  is  the  case  with 
the  two-port  motor — which  allows  the  incom- 
ing gases  to  enter  the  crank  case  during  the  en- 
tire upward  stroke  of  the  piston. 

It  will  thus  be  seen  that  the  piston  of  the 
two-cycle  motor  acts  as  a  pump  in  two  ways. 
First,  the  vacuum  is  formed  that  serves  to  draw 
the  charge  into  the  crank  case,  or  base,  of  the 
motor;  and  second,  the  return  stroke  of  the 


TWO-CYCLE  MOTORS       153 

piston  compresses  this  recently-inhaled  charge 
and  makes  it  ready  to  be  "  shot "  up  into  the 
cylinder  as  soon  as  the  piston  has  uncovered 
the  port  that  forms  the  upper  terminal  of  the 
communicating  passage.  There  can,  of  course, 
no  greater  amount  of  fresh  charge  enter  the 
cylinder  than  is  drawn  into  the  crank  case. 
Consequently,  the  amount  to  which  the  cylin- 
der will  be  filled  depends  upon  the  vacuum 
formed  and  the  pressure  exerted  upon  the 
charge  by  the  succeeding  downstroke  of  the  pis- 
ton. It  is  to  be  supposed  that  the  piston  rings 
will  be  tight  and  that  none  of  the  charge  can 
escape  by  them,  and  therefore  the  vacuum 
formed  and  pressure  exerted  in  the  crank  case 
will  depend  entirely  upon  the  displacement  of 
the  piston  in  its  travel  compared  with  the  total 
capacity  of  the  crank  case.  In  other  words,  if 
the  crank  case  is  large  and  the  piston  is  small 
and  travels  but  a  short  distance,  its  pump  ac- 
tion on  the  entire  volume  will  be  small.  But 
if  the  crank  case  is  small  and  the  travel  of  the 
piston  alternately  doubles  and  halves  the 
volume,  the  motion  of  the  piston  will  cause  the 
pressure  in  the  crank  case  to  vary  greatly. 

In  a  preceding  paragraph  it  has  been 
described  in  what  manner  the  incoming  charge 
in  the  two-cycle  motor  was  used  to  "  scavenge  " 


154    THE  GASOLINE  MOTOR 

the  cylinder,  or  rid  it  of  burned  gases,  by  de- 
flecting the  mixture  and  allowing  this  to  force 
out  the  remaining  exhaust  before  the  exhaust 
port  was  closed  by  the  upward  motion  of  the 
piston.  It  is  evident  that  the  greater  the  force, 
within  certain  limits,  with  which  the  charge 
enters  the  cylinder,  the  more  perfect  will  be  the 
scavenging  action.  But  there  is  a  limit  to  the 
pressure  that  can  be  attained  by  the  mixture 
when  it  is  compressed  in  the  crank  case  previ- 
ous to  its  discharge  into  the  cylinder.  This 
limit  is  determined  by  the  size  of  the  space  re- 
quired for  the  revolution  of  the  crank  and 
"  big  end  "  of  the  connecting  rod,  and  by  the 
volume  displaced  by  the  motion  of  the  piston. 
The  crank  must  have  room  in  which  to  revolve, 
and  the  displacement  of  the  piston  can  only  be 
the  area  of  its  top  multiplied  by  its  length  of 
stroke.  Thus  eight  pounds  per  square  inch  is 
about  the  usual  limit  of  crank  case  compression 
with  this  type  of  two-cycle  motor.  This  may 
be  varied  slightly  one  way  or  the  other  by  the 
arrangement  of  the  ports,  but  it  makes  slight 
difference  whether  the  motor  is  of  the  two-  or 
three-port  type  so  far  as  this  consideration  is 
concerned. 

Two-cycle  motors  have  been  designed  which 
combine  the  principles  of  action  of  both  the 


TWO-CYCLE  MOTORS       155 

two-  and  three-port  types.  The  most  import- 
ant departure  from  the  generally-accepted  type 
of  two-cycle  motor,  however,  is  the  design  in 
which  the  charge  is  fed  into  the  cylinder  from 
a  chamber  that  is  absolutely  independent  of 
the  crank  case  proper.  This  may  be  accom- 
plished in  several  ways.  There  may  be  what 
is  termed  a  "  differential  piston "  in  which  a 
separate  plunger  operates  in  the  interior  of  the 
hollow  "  trunk "  piston,  and  by  means  of  the 
proper  connection  with  the  crank  shaft  com- 
presses the  charge  in  the  chamber  thus  formed 
at  the  time  it  is  to  be  forced  into  the  cylinder. 
Another  design  for  obtaining  intake  com- 
pression independent  of  the  crank  case  con- 
sists of  a  collar,  or  circular  enlargement  at  the 
base  of  the  piston.  This  collar  reciprocates 
within  the  lower  portion  of  the  piston  in  a 
chamber  which  has  been  bored  to  the  exact  size. 
The  collar  consequently  forms  a  variable  base 
for  this  compartment,  and  as  the  piston  de- 
scends, the  collar  travels  with  it,  thus  drawing 
in  a  charge  of  the  fresh  mixture.  On  the  up- 
ward stroke,  this  mixture  is  compressed  by  the 
collar  as  it  reduces  the  size  of  the  compart- 
ment. It  will  be  seen  that  such  a  motor  can 
be  designed  to  compress  the  charge  to  almost 
any  amount. 


156    THE  GASOLINE  MOTOR 

Inasmuch  as  the  mixture,  as  mentioned 
above,  is  compressed  on  the  up-stroke  of  the 
piston,  it  is  evident  that  it  cannot  be  discharged 
into  that  particular  cylinder  at  that  time — for 
the  mixture  should  be  delivered  to  its  cylin- 
der only  when  the  piston  is  at  the  bottom  of 
its  stroke.  In  the  case  of  a  four-cylinder  en- 
gine, however,  one  of  the  pistons  would  be  in 
the  proper  position  for  the  entrance  of  the 
charge,  and  it  is  into  this  cylinder,  that  the 
compressed  mixture  is  forced.  The  compres- 
sion space  in  each  cylinder,  therefore,  works 
for  its  neighbor,  rather  than  for  itself. 

This  interchange  of  courtesies  is  obtained 
through  the  good  offices  of  a  distributor  in 
the  form  of  a  rotating,  hollow  cylinder  hav- 
ing ports  cut  throughout  its  length  that  register 
with  corresponding  passages  leading  to  the 
various  cylinders.  This  distributor  is  timed 
with  the  crank  shaft  of  the  motor,  and  may  be 
driven  either  by  a  gear  or  by  a  silent  chain. 
As  the  mixture  is  compressed  in  the  separate 
chamber  of  one  cylinder,  the  passage  leading 
to  the  distributor  is  opened  by  the  revolution 
of  the  latter,  and  the  charge  is  led  through  this 
passage,  the  distributor,  and  thence  through 
another  passage — also  opened  by  the  distri- 
butor— to  the  proper  cylinder.  The  cylinders 


TWO-CYCLE  MOTORS       157 

thus  operate  in  pairs,  one  receiving  its  charge 
while  the  other  is  about  to  begin  its  explosion 
stroke — and  vice  versa. 

The  force  of  the  explosion  in  a  gasoline  en- 
gine cylinder  is  not  only  dependent  upon  the 
amount  and  nature  of  the  inflammable  mixture 
admitted,  but  upon  the  force  with  which  it  is 
compressed,  as  well.  The  average  compres- 
sion pressure  of  a  two-  or  four-cycle  engine  of 
the  ordinary  type,  is  from  60  to  70  pounds  per 
square  inch.  Inasmuch  as  this  pressure,  as- 
suming that  the  rings  and  valves  are  tight,  is 
proportional  to  the  displacement  of  the  piston 
stroke  compared  with  the  volume  of  the  clear- 
ance space,  the  amount  of  compression  is  con- 
stant at  all  speeds  and  loads  of  the  motor. 
Should  it  be  possible  to  increase  this  compres- 
sion at  will,  it  would  be  found  that,  with  a 
warm  motor,  a  pressure  in  the  neighborhood  of 
100  pounds  per  square  inch  would  serve  to  gen- 
erate sufficient  heat  to  ignite  the  mixture  before 
the  formation  of  the  spark — for  it  is  one  of  the 
elementary  laws  of  physics  that  a  gas  will  be- 
come heated  when  compressed.  It  is  for  this 
reason  that  the  compression  pressure  of  the 
ordinary  automobile  motor  is  kept  in  the 
neighborhood  of  70  pounds  per  square  inch. 

A  method  of  varying  compression  pressure 


158    THE  GASOLINE  MOTOR 

to  meet  individual  load  requirements  has  been 
devised  for  some  motors,  however,  and  while 
such  types  are  not  as  yet  in  general  use  in  au- 
tomobiles, it  is  probable  that  the  near  future 
will  find  much  advancement  along  these  lines. 
One  such  two-cycle  motor  that  has  been  de- 
signed especially  for  automobile  use  employs 
a  separate  air  compressor  driven  by  the  en- 
gine itself  and  used  as  the  clutch  and  variable 
speed  transmission  of  the  car.  The  amount 
of  pressure  generated  in  the  compressor  is  de- 
pendent upon  the  resistance  offered  to  its  oper- 
ation— or,  in  other  words,  it  increases  with  ad- 
ditional load  carried  by  the  motor.  The  com- 
pression, or  compressed  air,  rather,  is  carried 
directly  from  the  compressor  to  the  cylinders 
of  the  motor,  being  admitted  at  the  proper 
time  by  a  rotary  valve  driven  by  the  crank 
shaft.  Thus  the  compression  in  each  cylinder 
is  automatically  regulated  by  the  load,  and  a 
motor  of  this  type  possesses  a  high  "  over- 
load "  capacity. 

The  motor  mentioned  above  operates  on 
somewhat  the  same  principles  as  those  found 
in  the  Diesel  engine,  which  will  be,  as  many 
predict,  the  ultimate  type  of  internal  combus- 
tion motor.  The  Diesel  motor  is  not  neces- 
sarily a  particular  make  of  engine,  but  bears 


TWO-CYCLE  MOTORS       159 

the  name  of  the  originator  of  the  principles 
involved.  These  are  distinct  from  those  of  the 
Otto  cycle,  which  is  the  principle  upon  which 
practically  all  automobile  motors  operate.  The 
Otto  cycle  consists  of  the  well-known  series 
of  events  in  the  cylinder,  as  follows :  Ignition, 
followed  by  the  explosion,  or  expansion  of  the 
burned  charge;  discharge  of  the  exhaust  gases, 
or  scavenging;  admission  of  the  fresh  charge, 
suction;  and  compression  of  the  newly-received 
mixture  previous  to  ignition  and  the  repetition 
of  the  cycle.  In  speaking  of  the  Otto  and 
Diesel  engines,  it  must  be  borne  in  mind  that 
they  are  referred  to  as  a  class,  rather  than  as 
a  particular  make — as  one  would  mention  pop- 
pet valve  or  sleeve  valve  engines — for  there 
may  be  many  manufacturers  of  each  type. 

Although  the  Diesel  principle  may  be  applied 
to  either  the  two  or  four-cycle  type  of  motor, 
it  is  to  the  former  design  that  it  lends  itself 
unusually  well.  This  motor  operates  a  two- 
stage  air  compressor  in  conjunction  with  a  stor- 
age tank.  At  the  beginning  of  the  compres- 
sion stroke,  pure  air  under  high  pressure  is  ad- 
mitted to  the  cylinder.  In  its  upward  travel, 
the  piston  compresses  this  air  to  a  pressure  ap- 
proximating 500  pounds  per  square  inch. 
While  it  has  been  shown  that  such  a  pressure 


160    THE  GASOLINE  MOTOR 

is  about  five  times  more  than  enough  to  gen- 
erate sufficient  heat  to  cause  premature  igni- 
tion, it  must  be  remembered  that,  unlike  the  or- 
dinary type  of  motor,  this  is  only  pure  air  that 
is  injected  into  the  cylinder  and  contains  none 
of  the  explosive  gasoline  vapor.  At  the  top 
of  the  stroke,  however,  when  the  compression 
is  at  its  maximum,  the  fuel  is  injected  directly 
into  the  cylinder  without  having  been  previ- 
ously vaporized. 

This  is  another  feature  in  which  the  Diesel 
motor  is  entirely  different  from  the  Otto  type, 
for  the  latter  must  employ  a  carburetor  to 
vaporize  the  fuel  before  it  can  be  admitted  to 
the  cylinder.  But  inasmuch  as  there  is  already 
a  pressure  approximating  500  pounds  per 
square  inch  in  the  cylinder  of  the  Diesel  motor 
at  the  time  the  fuel  is  injected,  there  must  be 
a  force  behind  the  latter  of  750  or  1,000 
pounds  per  square  inch  in  order  to  enable  it  to 
overcome  the  resistance  of  the  highly-com- 
pressed air  in  the  cylinder.  In  short,  the  liquid 
fuel  is  sprayed  directly  into  the  cylinder  at  a 
pressure  of  750  or  1,000  pounds  per  square 
inch.  This  tremendous  pressure  is  sufficient, 
not  only  to  vaporize  the  particles  of  fuel  as 
soon  as  they  enter  the  cylinder  from  the  noz- 
zle, or  "atomizer,"  but  to  cause  them  to  burst 


TWO-CYCLE!  MOTORS       161 

into  flame,  as  well.  In  other  words,  the  com- 
pression of  the  air  previously  has  generated 
sufficient  heat  in  the  cylinder  to  ignite  the  fuel 
immediately  on  its  admission. 

The  fuel  continues  to  be  injected  into  the 
cylinder  during  the  greater  part  of  the  down- 
stroke  of  the  piston.  In  this  respect,  also,  is 
the  Diesel  motor  radically  different  from  the 
Otto  type,  for  the  latter  receives  its  full  charge 
at  one  time  and  fires  the  entire  amount  in  a 
single  "  explosion."  In  the  Diesel  motor,  on 
the  other  hand,  the  ignition  continues  as  long 
as  fuel  is  admitted,  and  thus  this  engine  is  of 
the  internal  combustion  type  in  the  strictest 
sense  of  the  word.  It  is,  after  all,  the  expan- 
sion of  the  gases  due  to  the  heat  of  combustion 
that  produces  the  power  in  a  gasoline  engine, 
and  if  the  fuel  can  be  so  admitted  that  it  can 
burn  during  the  greater  part  of  the  stroke,  a 
high  efficiency  will  be  obtained. 

The  exhaust  gases  of  the  ordinary  two-cycle 
motor  pass  out  of  the  exhaust  port  as  it  is  un- 
covered by  the  descent  of  the  piston.  Those 
that  remain  are  forced  out  by  the  sudden  ad- 
mission of  the  fresh  charge,  which  is  deflected 
upward  and  is  intended  to  scavenge  the  top  of 
the  cylinder.  But  it  is  claimed  that  thus  employ- 
ing the  fresh  mixture  as  a  scavenging  agent  is 


162    THE  GASOLINE  MOTOR 

wasteful  of  the  fuel-permeated  charge  and  does 
not  conduce  to  efficient  running.  The  system 
is  simple  in  the  extreme,  however,  and  does  its 
work  well  in  small  installations  in  which  fuel 
economy  is  not  of  vital  importance.  But  in 
the  two-cycle  Diesel  type  of  engine,  the  high 
pressure  of  the  pure  air  is  used  for  scavenging, 
and  as  this  is  admitted  with  so  large  an  initial 
force,  the  exhaust  port  may  remain  uncovered 
for  a  longer  period  than  would  be  the  case  were 
the  air  to  rely  entirely  on  the  up-stroke  of  the 
piston  for  its  compression.  Then  too,  what- 
ever air  may  escape  contains  no  fuel,  and  con- 
sequently efficient  scavenging  may  be  obtained 
without  waste. 

At  the  high  pressure  at  which  the  fuel  is  in- 
jected into  the  cylinder  of  the  Diesel  engine, 
practically  any  grade  of  gasoline,  naphtha, 
kerosene,  crude  oil,  or  other  form  of  petroleum 
can  be  vaporized.  The  compressed  air  em- 
ployed in  the  compression  and  injection  of  the 
fuel  is  also  used  for  starting  the  motor,  for 
this  is  not  a  type  that  is  amenable  to  hand  crank- 
ing. Thus  the  Diesel  type  of  engine  can  be 
run  in  any  weather  on  any  grade  of  oil  fuel, 
and  as  the  carburetor  and  electrical  ignition 
system  are  absolutely  eliminated,  two  of  the 
great  sources  of  trouble  of  the  automobile 


TWO-CYCLE   MOTORS       163 

motor  are  absent — and  this  feature,  alone,  even 
more  than  the  superior  economy  of  operation, 
will  appeal  to  the  average  motorist. 

Just  when  this  type  of  motor  will  be  taken 
up  by  automobile  designers  is  difficult  to  state. 
The  Diesel  type  of  engine  has  proved  so  won- 
derfully successful  for  large  stationary  power 
plants  and  for  marine  purposes,  and  its  re- 
liability is  so  absolute  on  all  grades  of  fuel,  that 
this  motor  may  solve  the  failing-gasoline-sup- 
ply problem.  As  yet,  about  100  horsepower  is 
the  smallest  unit  that  has  been  made  in  any 
quantities,  but  it  was  recently  announced  that 
this  type  would,  in  the  very  near  future,  be 
built  for  motor  trucks  and  other  commercial 
vehicles.  Consequently,  it  is  well  for  all  those 
interested  in  the  application  of  the  two-cycle 
motor  to  the  automobile  to  understand  the  ele- 
mentary principles  on  which  this  radically-dif- 
ferent type  operates. 


THE  END 


VD/^V^If  C    The  new 

JD\J\Jf^O    outdoor  work  and  play 

d.  Each  book  deals  with  a  separate  subject 
and  deals  with  it  thoroughly.  If  you  want  to 
know  anything  about  Airedales  an  @JJT"1NG 
HANDBOOK  gives  you  all  you  want.  J£ 
it's  Apple  Growing,  another  <D  U  T*I  N  Q 
HANDBOOK  meets  your  need.  The  Fisher- 
man, the  Camper,  the  Poultry-raiser,  the  Auto- 
mobilist,  the  Horseman,  all  varieties  of  out- 
door enthusiasts,  will  find  separate  volumes  for 
their  separate  interests.  There  is  no  waste  space. 

Ct.  The  series  is  based  on  the  plan  of  one  sub- 
ject to  a  book  and  each  book  complete.  The 
authors  are  experts.  Each  book  has  been  spec- 
ially prepared  for  this  series  and  all  are  pub- 
lished in  uniform  style,  flexible  cloth  binding. 

Ct.  Two  hundred  titles  are  projected.  The 
series  covers  all  phases  of  outdoor  life,  from 
bee-keeping  to  big-game  shooting.  Among 
the  books  now  ready  or  in  preparation  are 
those  described  on  the  following  pages. 

OUTING'  PUBLISHING     COMPANY 

OUTING   MAGAZINE  >OCMir>S  OUTING  HANDBOOKS 

I4I-I45  WEST  3frTH  ST-NIW  YORK  122  S.MICHIOAN  AVE. CHICAGO 


THE  AIREDALE,  by  Williams  Haynes.      The  book 

opens  with  a  short  chapter  on  the  origin  and  development  of  the 
Airedale,  as  a  distinctive  breed.  The  author  then  takes  up  the 
problems  of  type  as  bearing  on  the  selection  of  the  dog,  breeding, 
training  and  use.  The  book  is  designed  for  the  non-professional  dog 
fancier,  who  wishes  common  sense  advice  which  does  not  involve 
elaborate  preparation  or  expenditure.  Chapters  are  included  on  the 
care  of  the  dog  in  the  kennel  and  simple  remedies  for  ordinary 
diseases. 

"//  ought  to  be  read  and  studied  by  every  Airedale  owner 
and  admirer.' ' — Howard  Keeler,  Airedale  Farm  Kennels. 

APPLE  GROWING,  by  M.  C.  Burritt.     The  various 

problems  confronting  the  apple  grower,  from  the  preparation  of  the 
soil  and  the  planting  of  the  trees  to  the  marketing  of  the  fruit,  are 
discussed  in  detail  by  the  author.  Chapter  headings  are: —  The 
Outlook  for  the  Growing  of  Apples— Planning  for  the  Orchard — 
Planting  and  Growing  the  Orchard — Pruning  the  Trees— Cultivation 
and  Cover  Cropping — Manuring  and  Fertilizing — Insects  and  Dis- 
eases Affecting  the  Apple — The  Principles  and  Practice  of  Spraying 
— Harvesting  and  Storing — Markets  and  Marketing — Some  Hints  on 
Renovating  Old  Orchards— The  Cost  of  Growing  Apples. 


THE  AUTOMOBILE— Its  Selection,  Care  and  Use, 
by  Robert  Sloss.  This  is  a  plain,  practical  discussion  of  the 
things  that  every  man  needs  to  know  if  he  is  to  buy  the  right  car 
and  get  the  most  out  of  it.  The  various  details  of  operation  and 
care  are  given  in  simple,  intelligent  terms.  From  it  the  car  owner 
can  easily  learn  the  mechanism  of  his  motor  and  the  "art  of  locating 
motor  trouble,  as  well  as  how  to  use  his  car  for  the  greatest  pleasure. 
A  chapter  is  included  on  building  garages. 

BACKWOODS  SURGERY  AND  MEDICINE,  by 

Charles  S.  Moody,  M.  D.  ATiandy  book  for  the  prudent  lover 
of  the  woods  who  doesn't  expect  to  be  ill  but  believes  in  being  on  the 
safe  side.  Common-sense  methods  for  the  treatment  of  the  ordinary 
wounds  and  accidents  are  described — setting  a  broken  limb,  reduc- 
ing a  dislocation,  caring  for  burns,  cuts,  etc.  Practical  remedies  for 
camp  diseases  are  recommended,  as  well  as  the  ordinary  indications 
of  the  most  probable  ailments.  Includes  a  list  of  the  necessary  med- 
ical and  surgical  supplies. 

'The  manager  of  a  mine  in  Nome,  Alaska,  writes  as  fol- 
lows: "/  have  been  on  the  trail  for  years  (twelve  in  the 
Klondike  and  Alaska)  and  have  always  wanted  just  such 
a  btok  as  Dr. Moody1 s Backwoods  Surgery  and  Medicine.' ' 


THE  BULL  TERRIER,    by  Williams  Haynes.     This 

is  a  companion  book  to  "The  Airedale"  and  "Scottish  and  Irish  Ter- 
riers" by  the  same  author.  Its  greatest  usefulness  is  as  a  guide  to 
the  dog  owner  who  wishes  to  be  his  own  kennel  manager.  A  full 
account  of  the  development  of  the  breed  is  given  as  also  description 
of  best  types  and  standards.  Recommendations  for  the  care  of 
the  dog  in  health  or  sickness  are  included.  The  chapter  heads 
cover  such  matters  as: — The  Bull  Terrier's  History — Training  the 
Bull  Terrier — The  Terrier  in  Health — Kennelling — Diseases. 

CAMP  COOKERY,    by  Horace  Kephart.    "The  leas 

a  man  carries  in  his  pack  the  more  he  must  carry  ip  his  head",  says 
Mr.  Kephart.  This  book  tells  what  a  man  should  carry  in  both  pack 
and  head.  Every  step  is  traced — the  selection  of  provisions  and 
utensils,  with  the  kind  and  quantity  of  each,  the  preparation  of  game, 
the  building  of  fires,  the  cooking  of  every  conceivable  kind  of  food 
that  the  camp  outfit  or  woods,  fields  or  streams  may  provide — even 
to  the  making  of  desserts.  Every  recipe  is  the  result  of  hard  practice 
and  long  experience.  Every  recipe  has  been  carefully  tested.  It  is 
the  book  for  the  man  who  wants  to  dine  well  and  wholesomely,  but 


in  true  wilderness  fashion  without  reliance  on  grocery  stores  or 
elaborate  camp  outfits.  It  is  adapted  equally  well  to  the  trips  of 
every  length  and  to  all  conditions  of  climate,  season  or  country;  the 
best  possible  companion  for  one  who  wants  to  travel  light  and  live 
well.  The  chapter  headings  tell  their  own  story.  Provisions — 
Utensils— Fires — Dressing  and  Keeping  Game  and  Fish — Meat- 
Game— Fish  and  Shell  Fish— Cured  Meats,  etc.— Eggs— BreadstufFs 
md  Cereals — Vegetables — Soups — Beverages  and  Desserts. 

"Camp  Cookery  is  destined  to  be  in  the  kit  of  every  tent 
dweller  in  the  country." — Edwin  Markham  in  the  San 
Francisco  Examiner. 

CANOE    AND    BOAT    BUILDING,     by     Victor 

SI  :>Clim.  All  of  us  like  to  think  we  could  build  a  boat  if  we  had 
to.  Mr.  Slocum  tells  us  how  to  do  it.  Designs  are  given  for  the 
vai  ous  types  of  canoes  as  well  as  full  descriptions  for  preparing  the 
ma  erial  and  putting  it  together.  Small  dories  and  lapstreak  boats 
axe  also  included. 


CATTLE  DISEASES,    by  B.  T.  Woodward.     Mr. 

Woodward  takes  up  in  detail  the  various  common  diseases  to  which 
cattle  are  liable.  His  book  is  designed  for  the  aid  of  the  practical 
farmer  in  cases  where  the  skilled  veterinarian  is  not  necessary.  A 
careful  description  of  the  various  diseases  is  given  and  the  accepted 
forms  of  treatment  stated. 

EXERCISE  AND  HEALTH,  by  Dr.  Woods  Hutch- 

lUSOn.  Dr.  Hutchinson  takes  the  common-sense  view  that  the 
greatest  problem  in  exercise  for  most  of  us  is  to  get  enough  of  the 
right  kind.  The  greatest  error  in  exercise  is  not  to  take  enough, 
and  the  greatest  danger  in  athletics  is  in  giving  them  up.  The  Chap- 
ter heads  are  illuminating.  Errors  in  Exercise — Exercise  and  the 
Heart— Muscle  Maketh  Man — The  Danger  of  Stopping  Athletics — 
Exercise  that  Rests.  It  is  written  in  a  direct  matter-of-fact  manner 
with  an  avoidance  of  medical  terms,  and  a  strong  emphasis  on  the 
rational,  all-round  manner  of  living  that  is  best  calculated  to  bring  a 
man  to  a  ^ ripe  old  age  with  little  illness  or  consciousness  of  bodily 
weakness. 

' '  One  of  the  most  readable  books  ever  written  on  physi- 
cal exercise."— Luther  H.  Gulick,  M.D.,  Department 
of  Child  Hygiene,  Russell  Sage  Foundation. 


ADVANCED  GOLF,  by  Harold  H.  HUton.    Mr.  Hil- 

ton  is  the  only  man  who  has  ever  held  the  amateur  championship 
of  Great  Britain  and  the  United  States  in  the  same  year.  In  addition 
to  this,  he  has,  for  years,  been  recognized  as  one  of  the  most  intelli- 
gent, steady  players  of  the  game  in  all  England.  This  book  is  a 
product  of  his  advanced  thought  and  experience  and  gives  the  reader 
sound  advice,  not  so  much  on  the  mere  swinging  of  clubs,  as  in  the 
actual  playing  of  the  game  with  all  the  factors  that  enter  in.  He 
discusses  the  use  of  the  wooden  clubs,  the  choice  of  clubs,  the  art  of 
approaching,  tournament  play  as  a  distinct  thing  in  itself,  and  kin- 
dred subjects* 


THE  FINE  ART  OF  FISHING,  by  Samuel  G.  Camp. 

Combines  the  pleasure  of  catching  fish  with  the  gratification  of  fol- 
lowing the  sport  in  the  most  approved  manner.  The  suggestions 
offered  are  helpful  to  beginner  and  expert  anglers.  The  range  of 
fish  and  fishing  conditions  covered  is  wide  and  includes  such  sub- 
jects as  "Casting  Fine  and  Far  Off",  "Strip-Casting  for  Bass",  "Fish- 
ing for  Mountain  Trout"  and  "Autumn  Fishing  for  J^ake  Trout". 
The  book  is  pervaded  with  a  spirit  of  love  for  the  streamside  and  the 
out-doors  generally  which  the  genuine  angler  will  appreciate.  A 
companion  book  to  "Fishing  Kits  and  Equipment".  The  advice  on 
outfitting  so  capably  given  in  that  book  is  supplemented  in  this  later 
work  by  equally  valuable  information  on  how  to  use  the  equipment. 

"frill  encourage  the  beginner  and  give  pleasure  to  the 

expert  fisherman."— N.  Y.  Sun. 

FISHING  KITS  AND  EQUIPMENT  by  Samuel  G. 

Camp.  A  complete  guide  to  the  angler  buying  a  new  outfit.  Every 
detail  of  the  fishing  kit  of  the  freshwater  angler  is  described,  from  rod- 
tip  to  creel,  and  clothing.  Special  emphasis  is  laid  on  outfitting  for 


fly  fishing,  but  full  instruction  is  also  given  to  the  man  who  wants 
to  catch  pickerel,  pike,  muskellunge,  lake-trout,  bass  and  other  fresh- 
water game  fishes.  Prices  are  quoted  for  all  articles  recommended 
and  the  approved  method  of  selecting  and  testing  the  various  rods, 
lines,  leaders,  etc.,  is  described. 

"A  complete  guide  to  the  angler  buyingjn  ne<w  outfit.19 — 

— Peoria  Herald. 

FISHING  WITH  FLOATING  FLIES  by  Samuel  G. 

Camp.  This  is  an  art  that  is  comparatively  new  in  this  country 
although  English  anglers  have  used  the  dry  fly  for  generations.  Mr. 
Camp  has  given  the  matter  special  study  and  is  one  of  the  few  Amer- 
ican anglers  who  really  understands  the  matter  from  the  selection  of 
the  outfit  to  the  landing  of  the  fish.  His  book  takes  up  the  process 
in  that  order,  namely — How  to  Outfit  for  Dry  Fly  Fishing — How, 
Where,  and  When  to  Cast — The  Selection  and  Use  of  Floating  Flies 
— Dry  Fly  Fishing  for  Brook,  Brown  and  Rainbow  Trout — Hooking, 
Playing  and  Landing — Practical  Hints  on  Dry  Fly  Fishing, 


THE  FOX  TERRIER,  by  Williams  Haynes.  As  in 
his  other  books  on  the  terrier,  Mr.  Haynes  takes  up  the  origin  and 
history  ot  the  breed,  its  types  and  standards,  and  the  more  exclusive 
representatives  down  to  the  present  time.  Training  the  Fox  Terrier 
— His  Care  and  Kenneling  in  Sickness  and  Health — and  the  Various 
Uses  to  Which  He  Can  be  Put — are  among  the  phases  handled. 

'    THE   GASOLINE   MOTOR,    by    Harold   Whiting 

Slauson.  Deals  with  the  practical  problems  of  motor  operation. 
The  standpoint  is  that  of  the  man  who  wishes  to  know  how  and 
why  gasoline  generates  power  and  something  about  the  various 
types.  Describes  in  detail  the  different  parts  of  motors  and  the 
faults  to  which  they  are  liable.  Also  gives  full  directions  as  to  re- 
pair and  upkeep.  Various  chapters  deal  with  Types  of  Motors — 
Valves — Bearings — Ignition  —  Carburetors  —  Lubrication  —  Fuel  — 
Two  Cycle  Motors. 

ICE  BOATING— CONSTRUCTION  AND  SAILING. 

illustrated  with  diagrams.  Here  have  been  brought  together 
all  available  information  on  the  organization  and  history  of  ice  boat- 
ing, the  building  of  the  various  types  of  ice  yachts,  from  the  small 
ISO-footer  to  the  600-foot  racer,  together  with  detailed  plans  and 
specifications.  Full  information  is  also  given  as  to  the  sailing  of  the 
various  types. 


HORSE,  THE— His  Breeding,  Care  and  Use,  by 
David  Buffum.  Mr.  Buffum  takes  up  the  common,  every-day 
problems  of  the  ordinary  horse-user,  such  as  feeding,  shoeing, 
simple  home  remedies,  breaking  and  the  cure  for  various  equine 
vices.  An  important  chapter  is  that  tracing  the  influx  ot  Arabian 
blood  into  the  English  and  American  horses  and  its  value  and  limi- 
tations. Chapters  are  included  on  draft-horses,  carriage  horses,  and 
the  development  of  the  two-minute  trotter.  It  is  distinctly  a  sensible 
book  for  the  sensible  man  who  wishes  to  know  how  he  can  improve 
his  horses  and  his  horsemanship  at  the  same  time. 

INTENSIVE  FARMING,  by  L.  C.  Corbett.  A  dis- 
cussion of  the  meaning,  method  and  value  of  intensive  methods  in 
agriculture.  This  book  is  designed  for  the  convenience  of  practical 
farmers  who  find  themselves  under  the  necessity  of  making  a  living 
out  of  high-priced  land. 


LAYING  OUT  THE  FARM  FOR 
PROFIT,  by  L.  G.  Dodge.      One  of  the 

farmers'  great  problems  is  to  put  every  acre  of 
his  land  to  the  best  possible  use.  This  book 
discusses  the  methods  oi  obtaining  this  result. 
The  author  is  an  investigator  for  the  Department 
of  Agriculture  and  has  given  particular  atten- 
tion to  this  subject. 


THE  MOTOR  BOAT— Its  Selection,  Care  and  Use, 
by  H.  W.  Slauson.  The  intending  purchaser  is  advised  as  to  the 
type  of  motor  boat  best  suited  to  his  particular  needs  and  how  to 
keep  it  in  running  condition  after  purchased.  The  Chapter  headings 
are:  Kinds  and  Uses  of  Motor  Boats — When  the  Motor  Balks — 
Speeding  of  the  Motor  Boat — Getting  More  Power  from  a  New  Motor 
— How  to  Install  a  Marine  Power  Plant — 
Accessories — Covers,  Canopies  and  Tops — 
Camping  and  Cruising — The  Boathouse. 


NAVIGATION  FOR  THE  AMA- 
TEUR, by  Capt.  E.  T.  Morton.  A  short 
treatise  on  the  simpler  methods  of  finding 
position  at  sea  by  the  observation  of  the  sun's 
altitude  and  the  use  of  the  sextant  and  chro- 
nometer. It  is  arranged  especially  for  yachts- 
men and  amateurs  who  wish  to  know  the  simpler  formulae  for  the 
necessary  navigation  involved  in  taking  a  boat  anywhere  off  shore. 
Illustrated  with  drawings.  Chapter  headings:  Fundamental  Terms — 
Time— The  Sumner  Line— The  Day's  Work,  Equal  Altitude,  and 
Ex-Meridian  Sights — Hints  on  Taking  Observations. 


OUTDOOR  PHOTOGRAPHY,  by  Julian  A.  Dimock. 

A  solution  of  all  the  problems  in  camera  work  out-of-doors.  The 
various  subjects  dealt  with  are  The  Camera — Lens  and  Plates— Light 
and  Exposure  —  Development — Prints  and  Printing —  Composi- 
tion^—jLandscapes  —  Figure  Work  —  Speed  Photography  —  The 
'  Leaping  Tarpon — Sea  Pictures — In  the  Good  Old 
Winter  Time— Wild  Life.  The  purpose  of  the  book 
is  to  serve  as  a  guide  not  only  for  the  man  or 
woman  who  has  just  taken  up  the  use  of  the 
camera,  but  also  for  those  who  have  progressed 
far  enough  to  know  some  of  the  problems  that 
confront  them. 


OUTDOOR  SIGNALLING,  by  Elbert  Wells.    Mr. 

Wells  has  perfected  a  method  of  signalling  by  means  of  wig-wag, 
light,  smoke,  or  whistle  which  is  as  simple  as  it  is  effective.  The 
fundamental  principle  can  be  learnt  in  ten  minutes  and  its  applica- 
tion is  far  easier  than  that  of  any  other  code  now  in  use.  It  permits 
also  the  use  of  cipher  and  can  be  adapted  to  almost  any  imaginable 
conditions  of  weather,  light,  or  topography. 


"I  find  it  to  be  the  simplest  and  most  practical  book  on 
signalling  published." — Frank  H.  Schrenk,  Director  of 
Camp  Belgrade. 

' '  One  of  the  finest  things  of  the  kind  I  have  ever  teen*  I 
believe  my  seven  year  old  boy  can  learn  to  use  this  system , 
and  I  know  that  we  will  find  it  very  useful  here  in  our 
Boy  Scout  work." — Lyman  G.  Haskell,  Physical  Direc- 
tor, T.  M.  C.  A.,  Jacksonville,  Fla. 


PACKING  AND  PORTAGING,  by  Dillon  Wallace. 

Mr.  Wallace  has  brought  together  in  one  volume  all  the  valuable 
information  on  the  different  ways  of  making  and  carrying  the 
different  kinds  of  packs.  The  ground  covered  ranges  from  man- 
packing  to  horse-packing,  from  the  use  of  the  tump  line  to  throwing 
the  diamond  hitch.  The  various  chapters  deal  with  Packing  and 
the  Outfit — The  Canoe  and  Its  Equipment — Camp  Equipment  for 
the  Canoe  Trip— Personal  Equipment — Food — The  Portage — Travel 
with  Saddle  and  Pack  Animals — Saddle  and  Pack  Equipment — 
Adjusting  the  Pack — Some  Practical  Hitches— Traveling  Without  a 
Pack  Horse— Afoot  in  Summer — With  Snowshoes  and  Toboggan — 
With  Dogs  and  Komatik. 

PRACTICAL  DOG  KEEPING,  By  Williams  Haynes. 

Mr.  Haynes  is  well  known  to  the  readers  of  the  OUTING  HAND- 
BOOKS as  the  author  of  books  on  Terriers.  His  new  book  is  some- 
what more  ambitious  in  that  it  carries  him  into  the  general  field  of 
Selection  of  Breeds,  The  Buying  and  Selling  of  Dogs,  The  Care  of 
Dogs  in  the  Kennels,  Handling  in  Bench  Shows  and  Field  Trials, 
and  at  considerable  length  into  such  subjects  as  food  and  feeding, 
exercise  and  grooming,  disease,  etc. 


PROFITABLE  BREEDS  OF  POULTRY,  by  Arthur 

S.  Wheeler.  Mr.  Wheeler  discusses  from  personal  experience 
the  best-known  general  purpose  breeds.  Advice  is  given  from  the 
standpoint  of  the  man  who  desires  results  in  eggs  and  stock  rather 
than  in  specimens  for  exhibition.  In  addition  to  a  careful  analysis 
of  stock — good  and  bad — and  some  conclusions  regarding  housing 
and  management,  the  author  writes  in  detail  regarding  Plymouth 
Rocks,  Wyandottes,  Orpingtons,  Rhode  Island  Reds,  Mediterraneans 
and  the  Cornish. 

"This  is  an  invaluable  book  for  those  who  would  make 
a  success  in  the  poultry  business." — Grand  'Rapids, 
(Mich.)  Herald. 

RIFLES    AND    RIFLE    SHOOTING,    by    Charles 

Askins.  A  practical  manual  describing  various  makes  and  mechan- 
isms, in  addition  to  discussing  in  detail  the  range  and  limitations  in 
the  use  of  the  rifle.  Among  other  things,  the  chapters  deal  with 


The  Development  of  the  American  Breech-Loading  Rifle — Single 
Rifle — Lever-Action    Repeater — Pump-Action   Repeater   and 


Shot 


Military  Bolt-Action— Double  Rifle— Rifle  and  Shotgun— Self-Loading 
Rifle — Rifle  Cartridges,  Miniature  and  Gallery — Small  Game — 
Match-Rifle  Cartridges  and  Their  Manipulation — High  Power, 
Small  Bore  Hunting  Cartridges — Big  Bore,  High  Power  Cartridges 
— Trajectory,  Accuracy,  and  Power  of  Hunting  Cartridges — Weight 
of  Rifle  and  Recoil — Stocks  and  Triggers — Rifle  Sights — Positions 
for  Rifle  Shooting — Outdoor  Target  Shooting, — Quick  Firing  and 
Running  Shots — Fancy  Snap  and  Wingshooting — Two-Hundred  Yard 
Sharpshooting. 

SCOTTISH  AND  IRISH  TERRIERS,  by  Williams 

Haynes.  This  is  a  companion  book  to  "The  Airedale",  and  deals 
with  the  history  and  development  of  both  breeds.  For  the  owner 
of  the  dog,  valuable  information  is  given  as  to  the  use  of  the 
terriers,  their  treatment  in  health,  their  treatment  when  sick,  the 
principles  of  dog  breeding,  and  dog  shows  and  rules. 

' '  The  happy  owner  of  a  terrier  for  the  first  time  could 
not  go  wrong  if  he  follows  Mr,  Haynes'  advice." — 
Brooklyn  Standard  Union. 


SPORTING  FIREARMS,  by  Horace  Kephart.    This 

book  is  the  result  of  painstaking  tests  and  experiments.  Practically 
nothing  is  taken  for  granted.  Part  I  deals  with  the  rifle,  and  Part 
II  with  the  shotgun.  The  man  seeking  guidance  in  the  selection 
and  use  of  small  firearms,  as  well  as  the  advanced  student  of  the 
subject,  will  receive  .an  unusual  amount  of  assistance  from  this  work. 
The  chapter  headings  are:  Rifles  and  Ammunition — The  Flight  of 
Bullets — Killing  Power — Rifle  Mechanism  and  Materials — Rifle 
Sights — Triggers  and  Stocks — Care  of  Rifle — Shot  Patterns  and 
Penetration  —  Gauges  and  Weights  —  Mechanism  and  Build  of 
Shotguns. 


TRACKS    AND    TRACKING,   by  Josef  Brunner. 

After  twenty  years  of  patient  study  and  practical  experience,  Mr. 
Brunner  can,  from  his  intimate  knowledge,  speak  with  authority  on 
this  subject.  "Tracks  and  Tracking"  shows  how  to  follow  intelli- 
gently even  the  most  intricate  animal  or  bird  tracks.  It  teaches 
how  to  interpret  tracks  of  wild  game  and  decipher  the  many  tell- 
tale signs  of  the  chase  that  would  otherwise  pass  unnoticed.  It 
proves  how  it  is  possible  to  tell  from  the  footprints  the  name,  sex, 
speed,  direction,  whether  and  how  wounded,  and  many  other  things 
about  wild  animals  and  birds.  All  material  has  been  gathered  first 
hand;  the  drawings  and  half-tones  from  photographs  form  an  im- 
portant part  of  the  work,  as  the  author  has  made  faithful  pictures  of 
the  tracks  and  signs  of  the  game  followed.  The  list  is:  The  White- 
Tailed  or  Virginia  Deer— The  Fan-Tailed  Deer— The  Mule-Deer— 
The  Wapiti  or  Elk— The  Moose— The  Mountain  Sheep— The 
Antelope— The  Bear— The  Cougar— The  Lynx— The  Domestic  Cat 
—The  Wolf— The  Coyote— The  Fox— The  Jack  Rabbit— The  Vary- 
ing Hare — The  Cottontail  Rabbit — The  Squirrel — The  Marten  and 
the  Black-Footed  Ferret— The  Otter— The  Mink— The  Ermine— Th« 
Beaver— The  Badger— The  Procupine— The  Skunk  —  Feathered 
Game— Upland  Birds— Waterfowl— Predatory  Birds.  This  book  is 
invaluable  to  the  novice  as  well  as  the  experienced  hunter. 
"This  book  studied  carefully,  will  enable  the  reader  to 
become  as  well  versed  in  tracking  lore  as  he  could  by 
years  of  actual  (xpfrifnct,"—Le<wifton  Journal. 


WING  AND  TRAP-SHOOTING,  by  Charles  Asking. 
The  only  practical  manual  in  existance  dealing  with  the  modern 
gun.  It  contains  a  full  discussion  of  the  various  methods,  such  as 
snap-shooting,  swing  and  half-swing,  discusses  the  flight  of  hirds 
with  reference  to  the  gunner's  problem  ot  lead  and  range  and  makes 
special  application  of  the  various  points  to  the  different  birds  com- 
monly shot  in  this  country.  A  chapter  is  included  on  trap  shooting 
and  the  book  closes  with  a  forceful  and  common-sense  presentation 
of  the  etiquette  of  the  field. 

"//  is  difficult  to  understand  how  anyone  who  takes  a  de- 
light in  hunting  can  afford  to  be  without  this  valuable 
book." — Chamber  of  Commerce  Bulletin,  Portland,  Ore. 
"This  book  will  prove  an  invaluable  manual  to  the  true 
sportsman,  whether  he  be  a  tyro  or  expert. "  —  'Book  News 
Monthly. 

"Its  closing  chapter  on  field  etiquette  deserves  careful 
reading." — N.  Y.  Times. 

THE  YACHTSMAN'S  HANDBOOK,  by  Herbert  L. 

Stone.  The  author  and  compiler  of  this  work  is  the  editor  of 
"Yachting".  He  treats  in  simple  language  of  the  many  problems 
confronting  the  amateur  sailor  and  motorboatman.  Handling 
ground  tackle,  handling  lines,  taking  soundings,  the  use  of  the  lead 
line,  care  and  use  of  sails,  yachting  etiquette,  are  all  given  careful 
attention.  Some  light  is  thrown  upon  the  operation  of  the  gasoline 
motor,  and  suggestions  are  made  for  the  avoidance  of  engine 
troubles. 

THE  STRATEGY  OF  TENNIS,    By  Raymond  D. 

Little.  Out  of  his  store  of  experience  as  a  successful  tennis  player, 
Mr.  Little  has  written  this  practical  guide  for  those  who  wish  to 
know  how  real  tennis  is  played.  He  tells  the  reader  when  and  how 
to  take  the  net;  discusses  the  relative  merits  of  the  back-court  and 
volleying  game  and  how  their  proper  balance  may  be  achieved; 
analyzes  and  appraises  the  twist  service,  and  shows  the  fundamental 
necessities  of  successful  doubles  plays. 

SUBURBAN  GARDENS,  By  Grace  Tabor.     Illus- 

trated  with  diagrams.  The  author  regards  the  house  and  grounds 
as  a  complete  unit  and  shows  how  best  results  may  be  obtained  by 
carrying  the  reader  in  detail  through  the  various  phases  of  designing 
the  garden,  with  the  levels  and  contours  necessary,  laying  out  the 
walks  and  paths,  planning  and  placing  arbors,  summer  Louses,  seats, 
etc.,  and  selecting  and  placing  trees,  shrubs,  vines,  and  flowers. 
Ideal  plans  for  plots  of  various  sizes  are  appended,  as  well  as  sug- 
gestions for  correcting  mistakes  that  have  been  made  through  "starting 
wrong." 


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